By Timothy Mclaughlin
(Reuters) - A man convicted of killing a woman and her two children after a break-in at their home in southern Missouri in 1998 was executed by lethal injection on Tuesday.
Mark Christeson, 37, was pronounced dead at 7:05 p.m. CST (0105 GMT on Wednesday), according to the Missouri Department of Corrections.
Christeson was sent to death row for the murders of Susan Brouk, her 12-year-old daughter, Adrian, and 9-year-old son, Kyle. Christeson raped the mother after breaking into the family's home with his cousin, according to court documents.
They drove the family to a pond where Christeson cut the throats of the mother and son and threw them into the water, court documents said. They suffocated the daughter and threw her into the pond, according to court documents.
The U.S. Supreme Court temporarily halted the execution in 2014 after Christeson's legal team argued his previous attorneys had failed to meet a key deadline for filing court papers in 2005 and had refused to cooperate when the mistake came to light.
The failure to meet the deadline meant Christeson's conviction in state court was never reviewed by a federal judge, which is the usual practice.
In January 2015, the Supreme Court threw out an appeals court ruling, denying Christeson another chance for his case to be heard.
His current attorney, Jennifer Merrigan, petitioned the Supreme Court for another stay of execution on Monday. The request was denied on Tuesday.
Christeson was also denied a clemency request by Missouri Governor Eric Greitens on Tuesday evening.
"Mark was 18 at the time of his crime and has an IQ of 74," Merrigan said by email on Monday.
"His execution may be unconstitutional, but the courts keep trying to rush him to the death chamber instead of giving him a fair opportunity in court."
Following Christeson's execution, there are 24 men on death row in Missouri, according to the Missouri Department of Corrections.
Last year, the state executed Earl Forrest, who was convicted of killing three people, including a sheriff's deputy, in a dispute over drugs in December 2002.
(Reporting by Timothy Mclaughlin in Chicago; Additional reporting by Alex Dobuzinskis in Los Angeles; Editing by Paul Simao and Peter Cooney)