Recently released footage from inside the jail cell of the "Golden State Killer" shows the elderly man, who seemed to rely on a wheelchair in court, is quite capable of standing on his own – and even of exercising.

“The truth of who Joseph DeAngelo is lies not just in what happened in the courthouse, but what has happened in his jail cell.”

— Sacramento County District Attorney Anne Marie Schubert

Video shared by the Sacramento County District Attorney’s Office on Friday – the same day Joseph DeAngelo handed down multiple consecutive life sentences – show the 74-year-old DeAngelo exercising and even climbing on the furniture in his jail cell.

'GOLDEN STATE KILLER' JOSEPH JAMES DEANGELO SENTENCED TO LIFE IN PRISON OVER STRING OF MURDERS, RAPES

“Over the last two years since the first day he was wheeled into the courtroom for his arraignment in a wheelchair in April of 2018, to the day of his plea on June 29, to this entire week sitting stone-faced in front of the world, each of us has witnessed a sociopath in action,” said District Attorney Anne Marie Schubert during a press conference following the sentencing. “The truth of who Joseph DeAngelo is lies not just in what happened in the courthouse, but what has happened in his jail cell.”

The footage in question is shown starting roughly four-and-a-half minutes into the video and was captured on at least three separate dates – June 1, June 17 and July 18, 2020.

It’s far from the weak-looking old man he was portrayed as being in court, starting at his arraignment more than two years ago in April 2018 through last week’s days of victim statements leading up to Friday’s sentencing.

'GOLDEN STATE KILLER' FACES EX-FIANCEE 'BONNIE' IN COURT AHEAD OF SENTENCING

DeAngelo, the former California police officer who lived a double life as the murderous sociopath dubbed the Golden State Killer, pleaded guilty in June to 13 murders and 13 rape-related charges that spanned much of California between 1975 and 1986. The plea deal spared him the death penalty.

Joseph James DeAngelo, sitting in a wheelchair, on the third day of victim impact statements at the Gordon D. Schaber Sacramento County Courthouse on Aug. 20, in Sacramento, Calif. (Santiago Mejia/San Francisco Chronicle via AP, Pool)

Joseph James DeAngelo, sitting in a wheelchair, on the third day of victim impact statements at the Gordon D. Schaber Sacramento County Courthouse on Aug. 20, in Sacramento, Calif. (Santiago Mejia/San Francisco Chronicle via AP, Pool)

He spoke for only a few seconds at his sentencing after rising from a wheelchair that the newly released jail video shows he doesn’t need.

"I listened to all your statements, each one of them, and I’m truly sorry for everyone I’ve hurt,” he said, putting aside the weak, quavering voice he used to plead guilty and also admit to multiple other sexual assaults for which the statute of limitations had expired.

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Prosecutors and victims said it was more evidence of a manipulative and vicious criminal who fooled investigators and his own family until he finally admitted victimizing at least 87 people at 53 separate crime scenes spanning 11 California counties. He was finally unmasked in 2018 with a pioneering use of DNA tracing.

The Associated Press contributed to this report.