FREMONT – Archana Kannan kept the lime green plastic silhouette of a crossing guard in front of her house so her two children could safely cross Lemonwood Street to play with the neighbors. When she noticed it missing one winter morning last year, she was baffled. A brand new child safety sign costs about $30 at Home Depot. Steal it? Really? Who would bother?
She complained to her neighbor but chalked it up to youthful hijinx – until a detective knocked on her door.
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Did she own a black, older-model Chevrolet Impala or Malibu? Was her husband home that night? the detective asked.
No and no.
Kannan didn’t understand where this was going until the detective told her a shocking story: A 20-year-old woman named Diamond and her boyfriend Alex had stolen the sign around 9:30 p.m. on Jan. 12, 2023, and thrown it into the back of their van.
Suddenly, someone in a black sedan was chasing them down Interstate 880. The driver pulled in front of them, slammed on the brakes and forced them to a stop in the fast lane. He jumped out and demanded the green plastic sign at gunpoint.
He also stole their keys, leaving them stranded in the middle of the dark freeway.
Standing in the median, Diamond was calling 911 for help when a Toyota Prius, swerving to avoid the van, struck her from behind. The impact sent her flying out of her checkered sneakers.
Diamond Ki’iLani Kamehaiku Sysco died where she landed.
Kannan couldn’t believe that this little sign meant to protect children could lead to such a horrible tragedy.
“I mean, why would they get mad at anybody for stealing my sign?” Kannan later told the Bay Area News Group. “It makes no sense.”
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A year had passed since Diamond’s death when her family and friends gathered Jan. 12 at Irvington Memorial Cemetery in Fremont. Her mother, Chasity Sisco, and stepfather, Joseph Martinez, brought folding chairs and large framed photos of Diamond, including one of her wearing a winter white knit cap. Her lashes are thick and long and her lips are pursed. She looks ready for a kiss.
Her older brother, Jack Sisco, stood over the flat gravestone embedded in the grass that is etched with her name and a phrase her family has adopted as a tribute: “Diamond’s World Forever.”
Daizy Bell, who had known Diamond since she was 9, choked up as she looked through the flowers and balloons that decorated the grave. How could Diamond be gone – over a silly plastic sign?
“There has to be a huge piece missing,” Bell said.
The mystery of Diamond’s death has sent her mother on an odyssey of frustrations and discoveries about a life her daughter had kept secret from her. The case has also led California Highway Patrol Detective Brian Phillips on a twisted path from the tragedy on the darkened freeway to a world of cars, characters and coincidences that are either too bizarre to believe or building blocks to a prosecution.
Now, 14 months after Diamond’s death, they could be enticingly close to cracking the case.
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A few blocks from Lemonwood Street, at the home Diamond shared with her parents, her mother has been trying to solve the mystery herself. She once took criminology classes in college and followed one of the first lessons: She created a crime wall.
“I had to work it like a Jane Doe,” Sisco said. “I couldn’t look at it and be so attached emotionally – or I would blind myself.”
With a black marker, she drew the crime scene directly onto the living room wall, starting with a straight line for I-880 South. That’s where Diamond and her 25-year-old boyfriend, Alex Dominguez, were driving as they began the 55-mile journey to Hollister to pick up a used Nissan 350Z. They had bought it for Diamond who, like her mother years ago, loved “wrenching” on hotrods, learning from the guys to make their cars louder and faster. She already owned a 1996 Ford Mustang Cobra SVT – a clone of the classic two-door. It didn’t run, but Dominguez had given it to her as a project for Christmas.
The Nissan was a souped-up rear-wheel drive, the kind of car popular in sideshows – where drivers do donuts in city intersections or stop traffic on the Bay Bridge.
Only after Diamond’s death, as her mother dove deeply into her daughter’s social media looking for clues, would Sisco discover that Diamond was part of that sideshow world. In videos of cars screeching in circles, with music thumping and headlights illuminating the spinning and the spectators, there was Diamond perched on the edge of the passenger window, her long black hair swirling in the wind.
Could the stolen children-at-play sign have had something to do with this world?
Sometimes, police familiar with sideshows say, drivers place the little neon-colored plastic figures in the intersection to circle around.
With every social media post and every message, Sisco was learning more about the life Diamond kept hidden.
“She was coming up. She’d been the side rider,” Sisco said. “All the illegal ones, my kid’s there.”
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On her crime wall, Sisco drew an outline of the van stuck in the fast lane along with an empty trailer hitched to the back that was meant to haul the Nissan home. She also drew a stick figure upside down to show where her daughter’s body came to rest: “Ki’iLani Girl,” she wrote. Ki’iLani means “image of heaven.”
The family, with Hawaiian roots, called her Ki, as in “key to her parents’ hearts,” her mother said. When Ki was born, her mother spelled her last name differently than her half-siblings, with a “y.”
And when she turned 18, Ki insisted everyone call her Diamond, her given first name.
For a young woman who enjoyed the male-dominated culture of cars, Diamond kept her bedroom girly, with “Live Laugh Love” spelled out in cursive across her pillowcases, a pink teddy bear from her dad on the nightstand, and a picture on the wall that says, “Always believe that something wonderful is going to happen.”
Diamond wanted to be a forensic scientist, but the pandemic stalled her plans to attend San Jose State. A neon vest she wore as a process assistant at a nearby Amazon warehouse still dangles on a hook. A poster of Albert Einstein hangs across from her bed. “Mom,” she once told Sisco, “if I could marry a man like this, I would.”
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Diamond and Dominguez had been dating for about six months and their friends considered them a happy couple. Presenting Diamond with the Mustang at Christmas was a grand gesture from Dominguez, who at the time worked at the Tesla dealership in Sunnyvale.
“He was like, ‘Here baby, I love you, here’s a Cobra. I know how much you love this car,’” said Dantae Akai, who helped them work on the car. “It had a brand new T45 transmission in it. The engine I just put in had custom motor mounts, custom radiator hoses. It’s a custom build.”
The carburetor was still giving them trouble. But Dantae said nothing seemed amiss between the couple or among their friends.
“Alex really didn’t have no enemies, nobody trolling for him,” Akai said. “He was an all-around good guy.”
He dismissed the idea that Diamond, or Dominguez, were involved much in sideshows. Who would want their car impounded by police? he asked. Besides, they all enjoyed “car meets” instead, where they hung out in parking lots, sucked down bobas from Tapioca Express, raised their hoods and showed off their exhaust pipes. Cops would show up when drivers revved their engines or burned out.
The Nissan down in Hollister would be their new obsession. But for some reason, on Jan. 12, 2023, the night they were set to pick it up, Dominguez was late – and Diamond was agitated.
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At home that night, Sisco wanted to celebrate her daughter’s new job as an administrative assistant. But when she gave Diamond a batch of custom-ordered Oreo cookies with “Diamond’s World” written in icing, her daughter barely noticed. Instead, she buried her head in her phone, texting.
“Something was off,” Sisco said.
When Dominguez finally showed up close to 8:30 p.m., the Ring camera at the front door captured the tension. The conversation is muffled and it’s not clear who she is talking about, but at one point Diamond says, “They don’t know where I live.”
As the young couple left the house and crossed the street to the van, Sisco noticed a black sedan pull to a stop in front of them. She thought it odd that Diamond and Dominguez didn’t acknowledge the driver in any way – almost as though they were avoiding eye contact.
A crude drawing of that sedan would later make Sisco’s crime wall: “Impala-Corolla,” she wrote.
That night, Sisco watched Dominguez climb behind the wheel of the van and the couple drive off with the trailer behind them.
About 20 minutes later, Sisco received her daughter’s frantic call.
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The Bay Area News Group attempted several times over the past year to interview Dominguez, but he didn’t respond. His mother, Tyana Dominguez, explained why.
“Due to the open investigation, we’re not allowed to talk to anybody and our attorney’s advice is not to say anything to anybody,” she said.
But Dominguez has shared his story in a text string with Diamond’s brother, Jack, and in an audio recording in an Instagram group chat.
“There is no way I can fully understand and process why it happened,” Dominguez wrote.
He did, however, describe what happened:
On their way to pick up the Nissan in Hollister, he and Diamond spotted the plastic children-at-play sign “in the middle of the street” on Lemonwood. “We both decided to remove it and put it in the van so it wouldn’t get destroyed because it was late at night,” he wrote in a puzzling explanation.
Minutes later on the freeway, he said a “black Chevy Impala, 2007” chased them down. He also revealed that a man in a white sedan was approaching close behind. Dominguez tried to change lanes and speed up. But the sedans overtook the van, boxing it in and jamming on their brakes.
Trapped in the far-left lane, Dominguez watched the two drivers come toward the van.
“They were cussing at us and threatened us and they had a gun on them and said, ‘Get out of the car. Where is the sign?’” Dominguez wrote.
The men forced open the van door, dragged out Dominguez and “beat me up and said, ‘Give us back the sign.’”
The attackers tried to steal the van, he said, “but I fought back because Diamond was in the car. I was attacking them and they took the van keys instead.”
“She was crying and I was tripping,” he said in the group chat.
Another detail stuck with him: As the men left, they were laughing.
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Standing in the median, Diamond called her mother.
“Mom, I just got robbed at gunpoint,” Sisco recalled her daughter telling her. Hang up and call 911, she told Diamond.
In his account, Dominguez said a Toyota Prius came “out of nowhere.” It was going so fast, he said, he felt like he was “getting slapped in the face by the wind.”
Then he heard something drop onto the asphalt. Diamond was blown out of her shoes and they “did like a bottle flip” before landing flat on the ground, he said.
When he reached Diamond’s side, she was coughing up blood.
“I said, ‘Oh my god, baby. No, no, no, no, no.’” he said. “This ain’t your time, baby. You’re the love of my life, baby. Don’t go, baby don’t go.’”
By then, a 911 dispatcher was sending the CHP to the tragedy unfolding just north of the Dixon Landing off-ramp.
“She has screamed,” the dispatcher said in a recording obtained by the Bay Area News Group, “and now is not, is not answering.”
Another detail from the dispatcher stood out, one that would haunt Diamond’s mother and hang over CHP Det. Phillips’ year-long quest to solve the case:
Diamond had been crying and told the dispatcher, “she knew who robbed her.”
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On the freeway, emergency lights cast an eerie red glow over the white tarp covering Diamond’s lifeless body.
Dominguez provided Phillips with a rough description of the man in the black Chevy. He had a mustache and was tall enough that Dominguez looked up to or at him – a key detail, the detective would later find. Dominguez said he didn’t get a good look at the man in the white sedan.
Unlike Diamond, Dominguez didn’t say he knew the men who robbed them and left them stranded.
Phillips took Dominguez’s phone to search for evidence. He later examined the records of Diamond’s phone that was destroyed in the crash. But no helpful clues emerged, Phillips said.
Then, a month later in February, Dominguez contacted the detective. He was convinced he had found the man in the black sedan, he told him. Searching Facebook, he tracked down a bald-headed man with a mustache he thought looked like the assailant and lived less than two miles from Lemonwood Street.
How exactly Dominguez found him and why he was so certain are unclear.
“It was a loose investigation he performed on his own,” Phillips said. The detective followed the lead for months, checking cell phone records and testing evidence from the van for a DNA match.
But he needed nothing more than to meet that man, Ricky Zook, in person to know he wasn’t the one they were looking for.
He was 5-foot-5.
“It can’t be him unless he had heels on,” Phillips said, “like six-inch heels.”
The detective was certain he had hit a dead end.
Then, a few days later on Sept. 1, his phone rang. It was Zook.
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Zook lives in an old Winnebago Chieftain RV with faded siding and a broken windshield. He used to park it in his grandmother’s driveway off Fremont Boulevard, but over the past few months, he’s moved it from place to place around town, changing parking spots every time someone complains.
He had settled on a frontage road along I-880 on a recent afternoon when a Bay Area News Group reporter met up with him.
Sitting on the gas tank of an old lawn mower he kept outside, he explained his shock when Det. Phillips showed up asking questions. Zook had spent more than a dozen years in prison on assault and other charges. He had no intention of going back.
“No, no, no. It was not me. I was nowhere near there,” Zook said.
He didn’t own any black or white sedan, he said, only a pair of RVs.
“I didn’t sleep for a month. I mean, I didn’t want them to come knocking on my door for a murder that I didn’t do, you know?”
He was so rattled that he, too, started asking his own questions. And that’s when the case took another turn.
Zook was visiting a friend, telling the story of the investigator knocking on his door and asking whether he had chased down a young couple on the freeway when the friend interrupted.
“Oh my God,” she said, “I know who did that.”
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How that story traveled through the neighborhood is spelled out in an Alameda County court record filed in November and mirrors Zook’s account. Zook had heard from the friend that her “sister’s ex-husband had talked about the incident,” the affidavit says. “The ex-husband allegedly related that he had stopped someone on the freeway and taken a sign from them and their keys.”
Zook told the Bay Area News Group that he had heard of the guy – they had had some kind of run in years earlier. He couldn’t remember his name, but knew where he lived. So he drove by the house, wrote down the address on the dashboard of his RV and called Det. Phillips.
A black Chevy sedan, Phillips would see, was parked out front.
When Phillips contacted the man by phone, he “denied being involved in the incident on the freeway or knowing about the incident,” the court document says.
In an interview, Phillips told the Bay Area News Group he later learned from cell phone tracking data that the man was “probably on the freeway or in the area” the night Diamond was killed. His DMV photo, Phillips said, matched Dominguez’s rough description: he was 6 feet tall with a mustache.
Zook’s story, the black Chevy, the cell phone data – all were enough for Phillips to reach back out to Diamond’s parents. With a picture of the man he had grabbed from social media, Phillips created a photo lineup and headed to the home of Diamond’s parents.
“If this doesn’t work,” Phillips said at the time, “we’re pretty much out of luck.”
In the living room of the family home, as Phillips laid out the photos, Diamond’s parents caught their breath.
“That motherf—-r was in my house,” her stepfather said.
The man in the photo, they told the detective, had called them after Diamond died.
He was interested in her Mustang.
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The red Mustang sat in the garage for months after Diamond’s death. The sight of it was so painful for her parents that Sisco could barely walk in.
So in August, Diamond’s stepfather drew up a flier advertising the 1996 Ford Mustang Cobra clone for sale. He hand-delivered it to homes around the neighborhood, especially ones that looked like car guys lived there, the ones with open garage doors and cars on blocks in the driveways.
He made a special trip to a house about a mile away that was always lined with old Chevys in various states of repair. He said he handed it to a man working in the garden who said he did odd jobs for the homeowner.
“My daughter got murdered. She got held up at gunpoint on the freeway at Dixon Landing,” Martinez said he told the man – the same story he told everyone he gave a flier. “This is her vehicle.”
The handyman said he would pass it on and within a couple of weeks, the couple said they got a call from the homeowner.
“He said he wasn’t really a Ford kind of guy, but ‘let me come check it out,’” Sisco recounted. “‘Maybe someone on my crew would know someone who’s interested.’”
When the man came to their house, Martinez said, he didn’t pay much notice to the car. He said he did some construction work, though, and the couple talked to him about doing a small home-repair job for a relative.
They also talked about Diamond and what happened to her. The living room was filled with her photos. Sisco even showed him Diamond’s bedroom.
“Has anyone been arrested?” Martinez said the man asked.
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The Bay Area News Group is not naming the man. He has not been arrested or charged.
In a phone interview, the man, in his 40s, said he never heard the story about Diamond “until I talked to her parents.”
When asked whether he had seen anyone steal a crossing guard sign, whether he had chased them to get it back, he said, “I have no idea what you’re talking about.”
He explained that he “got called for a job” by Diamond’s parents and “they stopped by my house and I did a job for them.”
He looked at the Mustang while he was at their home, he said, but he wasn’t interested.
“I’m a Chevy man,” he said.
The parents told him the story of Diamond’s death, he said, and “we got along really well because I have a daughter.”
At first, in his interview with this news organization, he denied ever talking to a detective about the case. But when prodded again, he acknowledged he did.
“He was investigating something that happened on a freeway,” he said, “and that was it.”
He didn’t know that Det. Phillips would access the whereabouts of the man’s cell phone, showing the phone had traveled from Fremont to the Dixon Landing Road area of I-880 that night, the detective told the Bay Area News Group.
One more thing the cell phone records showed?
Around the time of Diamond’s death, the detective said, a call from the Chevy man’s phone was placed to a phone registered to someone who lived on Lemonwood.
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More than a year after Diamond died, Phillips still has made no arrests. Solving the case seems so close, but just out of reach.
The detective said it isn’t clear who received that call from the Chevy man’s phone, and he wouldn’t reveal to which house on Lemonwood the phone was registered. Phillips did say he recently showed Diamond’s boyfriend a new photo lineup, but Dominguez told the detective that he didn’t recognize the Chevy man.
Then came another twist.
Last month, the Bay Area News Group found a resident on Lemonwood who recalled a neighbor telling him the morning after the sign disappeared about “something fishy” that happened: the neighbor saw people in a van take the sign and someone else he knew who was “driving through” chased after them “to get the license plate number.”
That same neighbor didn’t share that account when he spoke to the Bay Area News Group months back, and said at the time he didn’t know anything about the stolen sign.
Could he be the key to solving the case?
Despite knocks on the door, calls to relatives and a trip to the Central Valley to try to track down that neighbor, the Bay Area News Group couldn’t locate him. Det. Phillips said he managed to reach the man by phone, but didn’t get anywhere.
For now, nagging questions remain: Did the world of wrenching or sideshows have anything to do with Diamond’s fate? Did she really know the assailants?
And if this whole tragic episode was really about a vigilante intent on getting back a stolen child safety sign, why was it never returned?
“This never sat right with me. So that’s the hard part,” Phillips said. “I can’t imagine someone doing it over the sign.”
On Lemonwood Street, Kannan, whose sign was stolen to begin with, had nightmares for weeks that the plastic figure had come to life. When her husband offered to buy a new one, she told him that it had to be a different color. “The green man was haunted.”
Diamond’s red Mustang that she couldn’t get to start is now in the care of her childhood friend Daizy Bell, whose brother and husband are restoring it.
“When the guys got it running, there was a roar that shook my entire soul,” Bell said. “It literally shook the house, and I started to cry. She should have been the one to hear that.”
Diamond’s parents haven’t given up hope that justice will be done.
“Their time will come,” Martinez said.
He stops by the cemetery nearly every day, he said, tending the plastic flowers and keepsakes around her grave. If it’s late at night and the gates are closed, he parks on the street. The solar-powered angels the family tucked beside the flowers light up.
“I’ll just look at the light,” he said, “and tell her goodnight.”
After the vigil at the cemetery in January, Diamond’s mother had planned to return home and paint over the crime wall. She wanted it all “to go away,” she said, the heartache, the stress, the loss.
“But I couldn’t do it,” she said.
And she insists she won’t. Not until the mystery is solved.
Staff Writer Nate Gartrell contributed to this report.
Anyone with information about Diamond’s case is encouraged to call the CHP Investigations Tipline at 707-917-4491.
