The Green River Killer has been brought back to Seattle, booked into King County Jail

Gary Ridgway, known as the Green River Killer, was moved to the King County Jail in Seattle Monday.

Ridgway was booked into the King County Jail at 10:42 a.m. Monday, Sept. 9. The King County Sheriff's Office has him there on an "institutional hold."

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A Sheriff's Office spokesperson would not say exactly why Ridgway was moved to Seattle, but told KUOW, "Since Gary Ridgway’s arrest in 2001 pertaining to the Green River murder investigation, the King County Sheriff’s Office continues to actively investigate potentially related cases."

Ridgway was arrested in 2001 for more than 70 suspected murders spanning the 1980s and 1990s. He entered a plea bargain for 48 murder charges in 2003 and has since helped authorities locate and identify the remains of some of his victims. Modern DNA technology has also helped identify victims in recent years.

He has been sentenced with 49 life sentences. He hasn't been back to Seattle in 21 years, according to KOMO.

RELATED: DNA testing identifies teen victim of Green River Killer 4 decades later