A career criminal who has previously served five sentences in state prison is behind bars again, this time accused of three rapes. According to police, DNA evidence has linked the 51-year-old to rapes dating back to 2006.

Christopher Charles Sanders began serving prison time in August 1989, according to the Georgia Department of Corrections. Ten years later, he was in the middle of his fourth prison sentence following convictions on burglary and drug charges, records show.

After being released in July 2002, Sanders was a free man until April 2007, when he returned to prison. But during his time on the outside, he allegedly raped a woman inside his Marietta home, according to his arrest warrant.

RELATED: Rape kit backlog yields new leads in metro Atlanta cold cases

On the afternoon of Dec. 2, 2006, Sanders is accused of raping a woman, his arrest warrant states. Another suspect, Ryan Neal Walker, 41, was charged with aggravated sodomy during the same incident, according to police.

The victim was examined and DNA evidence was submitted to the GBI for testing, but not until December 2015. Both Sanders and Walker were identified as suspects, their arrest warrants state.

Though DNA was collected from victims of rapes in 2006, 2011 and 2012, the rape kits were not sent to the GBI until years later, according to the GBI. The test results identifying Sanders as the suspect were not released until January of this year. On Thursday, a grand jury indicted Sanders on three rape charges, the Cobb District Attorney’s Office said.

The GBI crime lab first began DNA testing in the early 90s, but evidence was not required to be submitted for all sex crimes. In 2016, Georgia passed a law requiring all stored rape kits be submitted to the GBI for testing. But by then, there was a backlog of thousands of cases. By April of this year, the state agency announced it had reduced its backlog by two-thirds, The Atlanta Journal-Constitution previously reported.

Earlier this year, the Metro Atlanta Sexual Assault Cold Case Task Force was formed so that old cases wouldn’t be overlooked. The task force includes law enforcement from Cobb and DeKalb counties, and the city of Atlanta. The cases against Sanders were investigated by the task force.

Ryan Neal Walker, 41, was arrested and charged with aggravated sodomy.  He was being held at the Cobb County jail without bond late Thursday.

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The cases involving Sanders were among those delayed by the GBI backlog. He is now in the Cobb jail, charged with three separate cases.

In May 2011, Sanders allegedly committed another rape after asking a woman to drive him to a convenience store, according to Marietta police.

“The accused began to make unwanted sexual advances towards (the woman) in her car while she provided him the transportation he requested,” the arrest warrant states. The woman told police she had told Sanders to stop and she ordered him out of her car.

Twenty minutes later, Sanders arrived at the woman’s home and entered by an unlocked door, according to police. He allegedly forced himself onto the woman and raped her. DNA samples obtained following the rape linked Sanders to the crime, his warrant states. Those samples were sent to the GBI in 2016.

On Oct. 26, 2012, Sanders allegedly raped a woman he knew inside a Cobb hotel room. After allegedly making unwanted advances, Sanders raped the woman in the early-morning hours, a third arrest warrant states. For a third time, DNA evidence linked Sanders to the incident.

Sanders was being held without bond Friday at the Cobb jail.

A two-woman team from Cobb County is part of a metro Atlanta task force that seeks to solve cold cases using previously untested rape kits