A US man who killed a hospital security guard and a sheriff’s deputy after escaping from custody in 2006 has been executed following an unsuccessful campaign to spare his life over concerns about his mental health.

William Morva, 35, was pronounced dead after the administration of a lethal injection at Greensville Correctional Centre in Jarratt, Virginia.

It was the first execution carried out in the state under a new protocol that makes more of the lethal injection procedure secret.

The execution came hours after Virginia’s Democratic governor announced that he would not spare Morva’s life despite pressure from mental health advocates, state legislators and lawyers who said his crimes were the result of a severe mental illness that made it impossible for him to distinguish between delusions and reality.

Morva, wearing jeans and a blue shirt, said “no” when he was asked whether he had any last words.

In denying a clemency petition, Governor Terry McAuliffe concluded Morva received a fair trial. He noted that experts who evaluated Morva at the time found he did not suffer from any illness that would have prevented him from understanding the consequences of his crimes.

He also said prison staff who monitored Morva for the past nine years had never reported any evidence of a severe mental illness or delusional disorder.

“I personally oppose the death penalty; however, I took an oath to uphold the laws of this Commonwealth regardless of my personal views of those laws, as long as they are being fairly and justly applied,” McAuliffe said in a statement.

Morva was awaiting trial on attempted robbery charges in 2005 when he was taken to hospital to treat an injury. He attacked a sheriff’s deputy with a metal toilet paper holder, stole his gun, and shot an unarmed security guard, Derrick McFarland, in the face before fleeing.

A day later, Morva killed another sheriff’s deputy with a bullet to the back of the head.

The deputy, Eric Sutphin, had been searching for Morva near Virginia Tech’s Blacksburg campus when he was shot.

Experts who examined Morva for his trial said he suffered from personality disorders that resulted in “odd beliefs”.

After his trial, a psychiatrist diagnosed him with delusional disorder, a more severe mental illness akin to schizophrenia that made him falsely believe, among other things, that he had life-threatening gastrointestinal issues and that a former presidential administration conspired with police to imprison him, his lawyers said. The lawyers argued that Morva escaped and killed the men because he was under the delusion that he was going to die in jail.

Morva was the first inmate executed in Virginia since officials made changes to the state protocol that have drawn fire from lawyers and transparency advocates.

The changes came after lawyers raised concerns in January about how long it took to place an IV line during the execution of convicted killer Ricky Gray.

Execution witnesses used to be able to watch inmates walk into the chamber and be strapped down.

A curtain would then be closed so the public could not see the placement of the IV and heart monitors.

After the curtain was reopened, inmates would be asked whether they had any final words before the chemicals started to flow.

At Morva’s execution, the curtain was closed when the witnesses entered the chamber and was not opened until he was strapped to the trolley and the IV lines were in place.

Virginia used a three-drug mixture obtained from a compounding pharmacy whose identify remains secret under state law.

Morva is the third prisoner to be executed since McAuliffe took office in 2014.

In April this year, McAuliffe granted mercy to Ivan Teleguz, saying jurors in the murder-for-hire case were given incorrect information that could have influenced sentencing.

Among those who campaigned for McAuliffe to spare Morva’s life were officials from the Hungarian embassy, two United Nations human rights experts and the daughter of the slain sheriff’s deputy.

“Our message and William’s story and his family’s story were resonating with a lot of people, and I don’t know why it didn’t resonate with the governor,” Morva’s attorney Dawn Davison said after her client’s execution.