JACKSONVILLE, Fla. -

Nearly two years after a 20-year-old woman was abducted and killed, police have filed a murder charge in the case.

Kenneth Thompson, 26, was long considered a person of interest in the January 2011 slaying of Michelle McCoy. He was the last person seen with McCoy the day she disappeared.

Thompson was arrested in connection with robbing a Metro PCS just a couple weeks after McCoy's disappearance. He was later convicted of armed robbery and other offenses in connection with that holdup and is serving a life sentence.

Thompson was returned from state prison to Duval County on Tuesday and booked on charges of kidnapping and murder.

The Metro PCS robbery is connected to, and the motive behind, McCoy's death, investigators said.

"We believe Kenneth and Michelle were acquaintances, they knew each other," said Lt. Rob Schoonover, of the Jacksonville Sheriff's Office. "She was in possession of a stolen item, a phone. We believe he was trying to get that phone back."

An autopsy report released last year is graphic in detailing how McCoy died slowly and violently.

All of McCoy's fingers and thumbs were cut off, her left leg was nearly amputated at the hip and her vertebrate was fractured, according to the report, which suggests torture or an attempt to keep her body from being identified. McCoy also suffered blunt force injuries to the face, neck and head, according to the report.

Some injuries appear to have been the result of McCoy being run over with a vehicle. There were burn marks all over her body that were post-mortem, according to the report.

The cause of death was listed as crushing blunt trauma.

DOCUMENT: Michelle McCoy Autopsy Report (Warning: Report contains graphic information)

McCoy was seen being dragged into a minivan by a group of people in Northwest Jacksonville on Jan. 10, 2011. She was reported missing Jan. 13, and police did not go public with her kidnapping for nearly three weeks. Her remains were found days later in a Northside lot.

Larry Thompson Tips also led police to their prime suspect in the abduction. Larry Thompson (pictured, right), a convicted rapist who pledged not to go back to jail, committed suicide during a SWAT standoff about a week after McCoy's remains were found.

No one had been charged with murder in McCoy's death until Thompson's nephew, Kenneth Thompson, was charged Tuesday.

According to a police report, Kenneth Thompson admitted he helped kidnap McCoy, but Larry Thompson strangled, pistol-whipped and drove over McCoy with their minivan.

"Whatever happened out there that night, they blunt force trauma and killed her and buried her in the ground," Schoonover said.

Kenneth Thompson went to trial in March this year for robbery. That's a key reason the murder charge took as long as it did to file and why Thompson didn't face the murder and kidnapping accusation in 2011.

"At that time, you got to look at the circumstances of the case, and what we had -- and the robbery was a strong charge, not saying murder is not -- but that was one to proceed with, get that out of the way and move on with the murder charge," Schoonover said.

McCoy's father and sister did not want to comment Wednesday on the murder charge being filed.

The state attorney's office released this statement on the murder charge:

"The investigation into Michelle McCoy's death has been exhaustive. We have worked tirelessly, with the Jacksonville Sheriff's Office Homicide Unit, to put the pieces of this puzzle together. While collecting information on what happened to Ms. McCoy, the State Attorney's Office was able to put Kenneth Thompson in prison for life on an unrelated robbery charge. While the SAO cannot discuss specific details of the murder and what led to Thompson's arrest, the SAO is ready to fight for justice for our victim Michelle McCoy."