ST. LOUIS (KTRS) –  Missouri  has carried out its first execution for this year.

Mark Christeson was executed on Tuesday evening. He was pronounced dead at 7:05 p.m.

Christeson was 18 when he and his 17-year-old cousin attacked Susan Brouk at her rural home in Vichy, then killed Brouk, her 12-year-old daughter and her 9-year-old son.

The cousins were caught after fleeing to California. Christeson’s cousin testified against him and was sentenced to life in prison without parole.

The U.S. Supreme Court denied a request by Christeson’s attorneys to halt his execution.