Gerald Lee Mitchell, 33, was pronounced dead at 6:25 p.m. CDT, shortly after receiving a lethal injection for the murder of 20-year-old Charles Marino during a robbery.
In his final statement, Mitchell expressed remorse to Marino's family.
"I am sorry for the pain," he said. "I am sorry for the life I took from you. I ask God for forgiveness and I ask you for the same. I know it may be hard, but I'm sorry for what I did."
Marino's sister, three cousins and a friend were witnesses to the execution as were four members of Mitchell's family.
"To my family I love each and every one of you," he said. "Be strong, know my love is always with you always. I know I am going home to be with the Lord. Shed tears of happiness for me. I love each and every one of you, keep on living."
Although Mitchell was a juvenile when he killed Marino, his case did not attract all the attention of Napoleon Beazley last summer in Texas and other juvenile killers whose cases have gone to the Supreme Court. The high court rejected Mitchell's final appeal earlier Monday.
Mitchell's lawyers took a different approach than other attorneys who argued a juvenile doesn't have the maturity to understand the gravity of the crime. They argued that Texas should be bound by international treaties that ban the execution of juvenile offenders.
Although Mitchell's execution went almost unnoticed by the news media, the head of the European Union was among several letter writers who urged Gov. Rick Perry to commute Mitchell's sentence, citing international laws against executing juvenile offenders.
In the Beazley case, questions were raised about the competency of his lawyer and the Texas Court of Criminal Appeals postponed his execution last August until it could hear arguments. The only issue in the Mitchell appeal was his age at the time of the crime.
Fifteen of the 38 states that permit the death penalty don't allow the execution of minors. Texas and four other states have a minimum age of 17 but some states drop the age as low as 16.
The Texas Board of Pardons and Paroles on Friday rejected requests for clemency and a 30-day reprieve for Mitchell.
Mitchell was convicted of capital murder in the 1985 robbery and slaying of Marino in a vacant house at Houston. Marino and his brother-in-law, Kenneth Fleming, 15, were robbed and shot when they attempted to buy marijuana from Mitchell. Fleming survived.
Mitchell was also convicted of attempted capital murder in the Fleming shooting and given 60 years in prison. He was also serving 60 years in the shooting death of Hector Manguia, who was shot the same day as Marino and Fleming in another robbery.
Mitchell was the 14th convicted killer executed this year in Texas. He was the 10th killer executed in Texas for a murder committed when he was a juvenile.