The Oklahoma State Bureau of Investigation (OSBI) told Fox News Digital that "it’s becoming more and more challenging" to find Veronica Butler and Jilian Kelley alive as the days mount with no signs of the missing Kansas women's whereabouts.

OSBI public information manager Hunter McKee made the comment Tuesday as it has now been 10 days since the women vanished while traveling to pick up children. Investigators say their vehicle was found abandoned on March 30 in a rural area of Oklahoma and "foul play" is suspected. 

"It’s a lot of land. Middle of nowhere, so searches still are continuing," McKee said. "We still are working on talking with multiple people and hopefully we can find something soon." 

"It’s been over a week," he added. "We are hopeful that we can find them alive, but obviously it’s becoming more and more challenging." 

OKLAHOMA INVESTIGATORS SEARCHING FOR MISSING WOMEN ARE ‘HOPEFUL THEY ARE ALIVE’ DESPITE SUSPECTED FOUL PLAY 

Veronica Butler and Jilian Kelley missing

Hugoton Assembly of God Pastor Tim Singer tells Fox News that Jilian Kelley, left, and Veronica Butler were heading to pick up Butler's children to bring them back to a birthday party in Hugoton, Kansas. (Texas County Sheriff's Office/Oklahoma Highway Patrol/Shutterstock)

The OSBI announced last Thursday that "Based on the information obtained from the victim’s [abandoned] vehicle, our investigators believe there was evidence to indicate foul play." 

A missing persons advisory from the Texas County Sheriff’s Office said that Butler has "several tattoos, a Chinese symbol on her left forearm, a sunflower on her left shoulder" and that "Jilian has a butterfly tattoo on her left forearm."    

SOUTH CAROLINA MAN VANISHES FROM CRUISE AFTER GETTING OFF AT POPULAR PORT OF COZUMEL, MEXICO 

Remote road in Oklahoma

The area near the Oklahoma-Kansas border where the vehicle the two women were traveling in was found abandoned on Saturday, according to the Oklahoma State Bureau of Investigation. (Google Maps)

The alert describes Butler as being 5 feet, 4 inches tall with red hair and green eyes, last seen wearing a blue short-sleeve shirt and denim shorts.    

Kelley has brown hair and blue eyes and was last seen wearing a long-sleeve shirt, blue jeans and tan or beige shoes, the alert adds.    

Veronica Butler and Jillian Kelley vanish in Oklahoma

Veronica Butler, left, and Jilian Kelley, have not been heard from since March 30. (Oklahoma Highway Patrol)

CLICK HERE TO GET THE FOX NEWS APP 

The vehicle they were traveling in was "found abandoned near Highway 95 and Road L, south of Elkhart, Kansas, in rural Texas County," according to the OSBI.