Oklahoma State Penitentiary's execution chamber was refurbished following an investigation into the botched lethal injection of Clayton Lockett on 29 April 2014
Texas executed its first inmate of 2016 on 20 January Reuters/Jenevieve Robbins/Texas Department of Criminal Justice

Texas executed its first prisoner of 2016 after a number of appeals failed to save the convicted killer from the death penalty. Richard Masterson was put to death on 20 January for killing a female impersonator in 2001 despite his last-ditch attempt convince the courts that the killing was unintentional.

The 43-year-old was pronounced dead at 6.53pm CT/12.53am GMT after receiving a lethal injection. According to the Associated Press, Masterson claimed the January 2001 strangulation murder of Darin Shane Honeycutt was an accident. His defence team submitted several appeals before the courts, including four in front of the US Supreme Court. His last ditch efforts for a stay of execution were all ejected.

Honeycutt, whose stage name was Brandi Houston, met Masterson at a bar and then went to Honeycutt's apartment. Masterson said he accidentally killed his 35-year-old victim when he attempted to put pressure on his neck to enhance the sexual experience. He said that Honeycutt then fell from the bed and was unresponsive.

Masterson told investigators that he believed Honeycutt was dead, so he fled the apartment, taking Honeycutt's vehicle with him and later dumping the car in Emerson, Georgia. He was later caught in Florida with another stolen car and confessed to the killing to police. According to the Intercept, Masterson had since recanted his confession.

Jurors at Masterson's trial were unconvinced of his innocence, particularly after Texas medical examiner Paul Shrode revealed that Honneycutt's autopsy revealed he had been killed by strangulation.

Masterson's attorney, Gregory Gardner, said that Shrode was influenced by his knowledge of the confession. The Intercept reported there was alleged evidence that suggests Honeycutt was not murdered, but instead suffered a fatal heart attack during sex.

According to the Texas Tribune, a day before his execution, Masterson's defence team filed last-minute requests for stays and new hearings in the US Supreme Court and the Texas Court of Criminal Appeals. His attorneys asked for a new hearing at the state level to challenge the constitutionality of a statue that allows Texas to keep execution drug manufacturers secret. That request was denied on the morning of 20 January.

At the federal level, Gardner argued that Honeycutt died of a heart attack after sex and that Shrode wrongly classified the death as a homicide. Shrode's credentials have been questioned and he was fired from his position of El Paso County chief medical examiner after a death row inmate in Ohio was granted clemency related to issues based on Shrode's testimony. Gardner argued that these facts were a cause for a stay and a hearing. Masterson's case even gained the attention of Pope Francis.

At least eight Texas death row inmates are scheduled for executions in the upcoming months, including one before the end of January. In 2015, Texas carried out 13 execution, accounting for almost half of the 28 executions around the US.