Updated

A Missouri man considered a person of interest in his ex-girlfriend's 2007 disappearance remains in jail after being charged with burning another missing woman's SUV.

Kylr Yust made his first court appearance on the felony knowingly burning charge Thursday. He's accused of torching 21-year-old Jessica Runions' small sport utility vehicle. The suburban Kansas City woman went missing last week. A judge entered a not guilty plea on Yust's behalf.

Police say Yust is a person of interest in his teenage ex-girlfriend's 2007 disappearance. Kara Kopetsky was last seen at her high school south of Kansas City.

Here's a look at the cases and the investigation:

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THE LATEST CASE

Yust hasn't been charged in Runions' disappearance and police haven't said whether he knows her. The woman from the Kansas City suburb of Raymore was last seen leaving a party on Sept. 8, and her SUV was found burned and abandoned two days later in Kansas City. Yust was arrested the next day. Police say they are treating it as a suspicious missing-person case.

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OTHER VICTIMS

Court records show 17-year-old Kopetsky filed for a protection order on April 30, 2007, alleging Yust kidnapped, restrained, choked, stalked and threatened to cut her throat during their nine-month relationship. A judge granted Kopetsky's request and scheduled a hearing for May 10, 2007, but Kopetsky went missing six days before that.

Police in Belton, where Kopetsky was last seen, say Yust is a person of interest in the case, but he hasn't been charged in the disappearance.

Yust spent time in jail for assaulting his pregnant then-girlfriend in 2011. The woman, who was 18 at the time of the incident, later won a protection order. She told authorities a drunken Yust choked her, threatened to kill her and told her he had "killed people before, even ex-girlfriends out of sheer jealousy."

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THE SUSPECT

Yust turned 28 on Wednesday. His father, Ken Yust, told The Associated Press he was heartbroken about his son's "crappy decisions," saying his behavior toward women has left "nothing but shame on this end."

Kylr Yust, who is on parole in a drug case, has said he started drinking alcohol at 11, first used cocaine at 14 and tried heroin by the time he was 16, according to The Kansas City Star, which cited court records.

Yust commented about Runions to a TV reporter Wednesday when he was about to be returned to Kansas City from the jail in Benton County, where he was arrested over the weekend. "I have no idea, sir," he told the KSHB reporter who asked what happened to Runions.

When asked if he killed Runions, Yust replied: "Did you?"

As he was placed into a police car, Yust said, "Hi, Mom."

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WHAT'S NEXT

The judge on Thursday ordered an evaluation to see if Yust is eligible for a public defender and scheduled his next court appearance for Sept. 29.

Investigators continue to look into the disappearances of Runions and Kopetsky.

Court records show investigators took two 9 mm bullets, clothing, Yust's hair samples and other items from a home in Benton County, southeast of Kansas City, where Yust spent time. A shirt and other items were seized from his grandfather's Kansas City-area home, according to media reports.