Virginia Department of Corrections via Reuters Inmate Robert Gleason Jr., seen in March 2011.

Updated at 9:45 p.m. ET: PORTSMOUTH, Va. - An inmate who pleaded guilty to two prison murders and threatened to continue killing until he received the death penalty was pronounced dead at 9:08 p.m. on Wednesday, marking the first execution of the year in the U.S. and the first time Virginia used its electric chair in nearly three years.

Robert Charles Gleason Jr., 42, chose electrocution over lethal injection, the more commonly used method for executions in the United States. Gleason was serving life in prison for a 2007 murder when he killed his cellmate in 2009. He strangled another inmate in 2010.

The oak armchair in which Gleason was secured with leather straps on Wednesday is the same chair Virginia used for its first electrocution, which was carried out at the old Virginia State Penitentiary in 1908. The way the chair delivers the electric shocks was updated in 1991.

Gleason told AP in phone interviews that he deserved to die for what he did.

"The death part don't bother me. This has been a long time coming," he said in one of the many interviews from death row. "It's called karma."

Gleason said he requested death in order to keep a promise to a loved one that he wouldn't kill again. He said doing so would allow him to teach his children, including two young sons, what could happen if they followed in his footsteps.

"I wasn't there as a father and I'm hoping that I can do one last good thing," he said previously. "Hopefully, this is a good thing."

Gleason waived appeals and volunteered to be executed over the objections of his former court-appointed attorneys, who argued that his time spent in solitary confinement while on death row left him unable to make rational decisions.

State and federal courts rejected efforts by his attorneys to halt the execution and have Gleason ruled mentally incompetent. Virginia Governor Bob McDonnell said last week he would not intervene.

"Gleason has expressed no remorse for these horrific murders," McDonnell said in a statement on Friday. "He has been found competent by the appropriate courts to make all of these decisions."

Gleason was serving life in prison without parole for a 2007 murder when he admitted to using strips from bed sheets to bind and strangle fellow inmate Harvey Watson, 63, at Virginia's Wallens Ridge State Prison in May 2009.

He said he was able to tie Watson's hands without a struggle by saying it was part of an escape plan. He taunted Watson before he strangled him by pressing a urine-soaked sponge onto his face and a sock into his mouth, court records said.

Gleason told authorities he timed that murder for the second anniversary of his earlier homicide, according to court records.

Another strangulation

A year later, while awaiting sentencing, Gleason attacked another inmate in July 2010 at the super maximum-security Red Onion State Prison, court records said.

Gleason said he asked Aaron A. Cooper, 26, to try on a "religious necklace," which Gleason threaded through wire fencing that separated their individual cages in a recreation yard.

Gleason testified that he choked Cooper through the fence "till he turned purple," waited for his color to come back and then proceeded to choke Cooper to death.

As officers tried to resuscitate Cooper -- video surveillance shows had been choked on and off for nearly an hour -- Gleason told them "you're going to have to pump a lot harder than that."

The second strangulation prompted a federal wrongful death lawsuit by Cooper's mother, who accuses corrections employees of giving Gleason the chance to murder her son after Gleason told guards he would kill again.

Dena Potter of The Associated Press contributed to this report.

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