The US Supreme Court Tuesday declined to block the execution of Missouri inmate Leonard Taylor despite new evidence potentially proving a wrongful conviction. Taylor died by lethal injection at the state prison in Bonne Terre on Tuesday.

Taylor was convicted of the murders of his girlfriend Angela Rowe and her three children in 2004 but continually maintained that he was innocent and that he was in California when the crime took place. Last month, Taylor’s attorney filed a request under Missouri law for a hearing to consider new evidence which could prove a wrongful conviction. Two petitions were denied by the Missouri Supreme Court before being rejected by the US Supreme Court.

Initially, investigators said that the victims had been killed three days before their bodies were found. At trial, prosecutors alleged that three weeks passed between the murders and the discovery, according to The Kansas City Star. Lawyers for Taylor argued that evidence proved that Rowe and her children were still alive at the time Taylor was in California. Such evidence includes the testimony of forensic pathologist Dr. Jane Turne, who discredited the time of the victims’ deaths stated at trial, as well as other witnesses who supported Taylor’s claim of innocence.

Reacting to Taylor’s sentencing, Co-Director of Missourians Alternatives to the Death Penalty Michelle Smith stressed the need for accountability in “the decades of prosecutorial misconduct, racist biases and targeting of the poor and marginalised” in death row cases. Taylor is one of 29 individuals sentenced to death by Missouri prosecutor Bob McCulloch and the third person to be executed by Missouri in the last 10 weeks.

Protestors gathered across the state to express opposition to the execution amongst wider spread commendation by local campaign groups including the Eighth Amendment Project and the Midwest Innocence Project. Governor Mike Parson stated that “despite his self-serving claim of innocence, the facts of his guilt in this gruesome quadruple homicide remain.”