A Texas man who said his death sentence was based on false and unscientific expert testimony was executed Thursday evening for killing a man during a robbery decades ago.

Brent Ray Brewer, 53, received a lethal injection at the state penitentiary in Huntsville for the April 1990 death of Robert Laminack. The inmate was pronounced dead at 6:39 p.m. local time, 15 minutes after the chemicals began flowing.

Prosecutors had said Laminack, 66, gave Brewer and his girlfriend a ride to a Salvation Army location in Amarillo when he was stabbed in the neck and robbed of $140.

Brewer’s execution came hours after the U.S. Supreme Court declined to step in over the inmate’s claims that prosecutors had relied on false and discredited expert testimony at his 2009 resentencing trial.