ST. LOUIS COUNTY, Mo. – A man who was found guilty of killing his girlfriend and her three young children in Jennings, Missouri, will be put to death Tuesday night.

There have been multiple efforts to try and stop the execution of Leonard Taylor, but so far they have all failed. One of the last attempts to spare his life came up short when Governor Mike Parson denied clemency for Taylor Monday.

Taylor was convicted in 2008 of the quadruple murder. The 58-year-old is set to die by lethal injection at the state prison in Bonne Terre.

Taylor has maintained his innocence in this case, saying he was in California when the murders happened in 2004, but the courts have disagreed.

Former St. Louis County Prosecuting Attorney Bob McCulloch, whose office prosecuted Taylor, calls his claims of innocence nonsense and says the evidence against him is overwhelming.

Taylor was convicted of shooting and killing his girlfriend 28-year-old Angela Rowe and her three children – 10-year-old Alexus Conley, 6-year-old AcQreya Conley and 5-year-old Tyrese Conley.

The murders happened at Rowe’s home in Jennings.

Current St. Louis County Prosecuting Attorney Wesley Bell announced last week that he would not be filing a motion to vacate Taylor’s sentence. Explaining, that the facts are not there to support a credible case of innocence.

The Missouri Supreme Court also denied a stay last week.

In denying clemency Monday, Governor Parson released a statement reading in part:

“Despite his self-serving claim of innocence, the facts of his guilt in this gruesome quadruple homicide remain. The State of Missouri will carry out Taylor’s sentences according to the court’s order and deliver justice for the four innocent lives he stole.”

If Taylor’s death sentence is carried out, it would be Missouri’s third execution in the past three months.