HUNTSVILLE: Texas executed a Houston man on Thursday convicted in the 1988 killing of a teenager and her toddler cousin, a prison spokesman said.

Preston Hughes, 46, was convicted of stabbing to death 15-year-old Shandra Charles and her 3-year-old cousin, Marcell Taylor, in a vacant field near his apartment complex.

Hughes was executed at 7:52pm Central Time. He was the 40th inmate executed in the United States this year and the 15th in Texas.

Hughes had maintained his innocence, first saying the deaths were an accident and then contending that he had nothing to do with them and that police had framed him. At the time, Hughes had been free on probation for the aggravated sexual assault of a 13-year-old girl.

In his final statement on Thursday night, Hughes continued to maintain his innocence, according to a transcript provided by the Texas Department of Criminal Justice.

There was no DNA evidence linking him directly to the killings. Advocates and Hughes’ lawyer insisted there were too many weaknesses in the case and that the evidence against him was either circumstantial or fabricated.