John Carter has been arrested in connection with her death.
More than a decade after an Ohio woman disappeared, her then-fiance has been arrested in connection with her death.
John Allen Carter, 35, was arrested Wednesday and booked in the Butler County Jail in Hamilton, Ohio, where he remained in custody as of Thursday, according to online jail records. It was unclear whether he has an attorney.
He has been charged with two counts of felony murder, according to Cincinnati ABC affiliate WCPO, which cited the Butler County Prosecutor's Office. ABC News has reached out to the prosecutor's office for comment.
Carter was believed to be the last person to see Katelyn Markham alive before she vanished in the summer of 2011. Markham was a 22-year-old college student residing in the Cincinnati suburb of Fairfield and was engaged to Carter at the time of her disappearance.
"We all suspected that he had something to do with it," Markham's father, Dave, told WCPO on Wednesday.
Carter called 911 to report Markham missing after she stopped responding to his text messages and didn't show up for work on Aug. 14, 2011, two days before her 23rd birthday. The couple had plans to move to Colorado in November, after Markham was expected to finish her bachelor's degree in graphic design.
"I went to her house and she was gone without her car, without her purse, without her keys," Carter told ABC News during an interview in August 2011.
"My gut feeling is that she's alive and that she's OK," he added. "I have to believe she's alive. I have to believe that I'm going to have her in my arms soon."
Authorities and volunteers, including Carter, searched for Markham for years. On April 7, 2013, Markham's remains were found in garbage bag at a dump site along Big Cedar Creek in southeastern Indiana, near the state line with Ohio, about 30 miles west of her home. Markham's death was ruled a homicide but the cause was unknown, according to WCPO.
The case went cold for years despite being featured in television shows and a documentary, the efforts of multiple law enforcement agencies and a $100,000 reward for information.
Then, in February, one of Markham's friends -- 35-year-old Jonathan Palmerton -- was arrested and charged with felony perjury in connection with her death, WCPO reported. That same day, authorities executed search warrants at Carter's former home in Fairfield, where his mother lives, as well as at other residences of friends' relatives. Investigators also excavated the backyards looking for evidence. Carter was not arrested at that time, according to WCPO.
Upon learning about Carter's arrest on Wednesday, Markham's father said he felt "relieved."
"Everybody's thrilled that this is ending," he told WCPO. "I think myself and a lot of other people were expecting this and were waiting for this for 12 years."
ABC News' Ahmad Hemingway and Jessica Hopper contributed to this report.