The Coxes said they are supporting several changes to the system, including more rights for grandparents in court proceedings. They pushed restrictions on private home visitations, arguing that they had been concerned about allowing Powell to visit with the children while only one woman supervised the meeting.
Chuck Cox also said he was bothered by the state's persistent focus on trying to reunify children with their biological parents, especially when there are safety concerns.
"It just flies in the face of reason," he said.
The Coxes and their attorneys are also backing a bill that would prohibit a child custody award to a murder suspect. Powell's wife, Susan, has been missing since 2009 but Utah authorities never publicly labeled her disappearance as a murder. Investigators also never called Powell a suspect.
Powell maintained full care of his children until last summer, when his father was arrested on voyeurism and child pornography charges. The state then shifted custody to the Coxes but allowed Josh to have a few hours of supervised visitation each week.
On one of those visits earlier this month, Powell locked the visit supervisor out of the home, used a hatchet on the boys and then burned down the house.
Powell's actions came just days after a psychologist recommended that he undergo a specialized psychosexual evaluation. Utah authorities had recently disclosed incestuous images that had been uncovered in a search warrant at Powell's home two years ago.
The state's Department of Social and Health Services also formed a team that will review the deaths of Charlie and Braden Powell. That panel, which is set to meet at the end of April, includes a psychologist that specializes in sex offender treatment law enforcement.