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.
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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.
Christeson's cousin Jesse Carter, who at 17 was one year younger than him at the time of the slayings, testified against Christeson at trial and received a sentence of life in prison, according to the St. Louis Post-Dispatch.
The U.S. Supreme Court temporarily halted Christeson's execution in 2014 after his legal team argued his previous attorneys 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."
Greitens in a statement describing the victims said Adrian wanted to become a veterenarian or a teacher and Kyle wanted to be an Army officer.
Christeson in a written statement before his execution said he loved his family and was "more than blessed" to have them.
Following Christeson's execution, 24 men remain on death row in Missouri, according to the Missouri Department of Corrections.
(Reporting by Timothy Mclaughlin in Chicago; Additional reporting by Alex Dobuzinskis in Los Angeles; Editing by Peter Cooney and Lisa Shumaker)