Runions was last seen leaving a party in south Kansas City on September 8.
The remains of one of two people discovered in a rural area this week belong to a 21-year-old Missouri woman who vanished in September, authorities said Thursday.
A medical examiner positively identified the remains as Jessica Runions, who was last seen leaving a party in south Kansas City on September 8, the Cass County Sheriff’s Office said on Wednesday.
Her burned out vehicle was found two days later.
The party’s host reportedly told Runions' family that she left with 28-year-old Kylr Yust, a friend of her boyfriend.
He was arrested and charged with knowingly burning Runions’ car, cops said.
A judge entered a not guilty plea on his behalf. His trial is set for October.
Yust had been previously questioned in the disappearance of his ex-girlfriend Kara Kopetsky, who was 17 years old when she was last seen at Belton High School on May 4, 2007.
Read: Police Meet With Families of Missing Women After Unidentified Remains Are Discovered
Kopetsky disappeared just days after filing an order of protection against Yust, who she claimed kidnapped and restrained her, choked her and threatened to cut her throat during their nine-month relationship, according to a filing obtained by The Associated Press.
The remains of the second person discovered about 20 miles away from Kansas City have not yet been identified, police said.
Kopetsky’s mother, Rhonda Beckford, told KCTV that the second set of remains could take months, if not a year, to identify.
She and Runions’ loved ones were contacted by police after the remains were uncovered by a mushroom hunter earlier this week.
"We need a resolution to this," Beckford told reporters after their meeting with police.
She spoke as Runions' mother, Jamie Runions, stood by her side.
Read: Missing College Student's Remains Found In Shallow Grave, Boyfriend Charged
"We need to find out," she continued.
Jamie Runions took to social media after officials determined her daughter’s remains had been found, posting, "No matter what, I will never let you go."
Friends responded to the mother’s post, offering their condolences and prayers for her daughter, who they said was taken too soon.
"I’m so so sorry. I’ll always remember the sweet little girl that she was," one commenter wrote.
"Jamie, there are no words to tell you how sorry I am for the pain that you and the entire family are going through! I am sending you all my love and keeping you all in my prayers," another person posted.
Yust has not been charged in the disappearance of Runions or Kopetsky.
Nearly 100 investigators were expected to search the area where the remains were discovered Thursday, officials said.
Watch: Searchers Emotional Over Finding Remains of Hiker Missing 2 Years
