A former Dent County sheriff's deputy and state correctional officer has been convicted of killing his ex-girlfriend and her boyfriend during a child custody dispute.

Marvin Rice was found guilty Thursday in St. Charles County of first-degree murder in the 2011 deaths of Annette Durham, 32, and second-degree murder in the death of Steven Strotkamp, 39, in 2011, The St. Louis Post-Dispatch reported .

The sentencing phase begins Friday. Prosecutors are seeking the death penalty.

Rice and Durham had been arguing over custody of their son, prosecutors said.

They had had an affair while he was a Dent County sheriff's deputy. Durham, who struggled with drug addiction, was jailed several times and the boy was born in 2010 while she was in prison. Rice and his wife took care of the child but no formal agreement was in place, Dent County Prosecuting Attorney Andrew Curley said during the trial.

When Durham got out of prison in 2011, she decided to get her life together and establish a relationship with her son, Curley said.

Rice initially allowed her only brief supervised visits with the boy. On Dec. 10, 2011, she was allowed an unsupervised visit and decided that she wanted to keep her son overnight, Curley said.

That prompted Rice to go to the home outside Salem where Durham and Strotkamp lived. He shot the couple with a .40-caliber pistol, took his son and gave the boy to his wife before leading police on a chase that ended in a shootout in a Jefferson City hotel during a Christmas party, Curley said.

Curley said Strotkamp identified Rice as his killer before he died. Durham's daughter testified that she saw Rice with a pistol before he left with the boy.

Public defender Charles Hoskins told jurors that Rice "snapped" when Durham told him, "You're never seeing (your son) again, and neither is your family." He argued that Rice was under "extreme emotional distress" at the time and that a pituitary tumor and the 17 medications he was taking affected his impulse control and made him paranoid. He also argued that Rice didn't have "cool reflection" necessary to convict him of first-degree murder.


Information from: St. Louis Post-Dispatch, http://www.stltoday.com