Steven Hayes is unlikely to commit serious violence if he spends his life in prison, a defense expert testified Tuesday.
A jury is hearing testimony in a New Haven court to decide whether Hayes should he imprisoned for life or executed for killing Jennifer Hawke-Petit and her daughters, 17-year-old Hayley and 11-year-old Michaela, inside their Cheshire home during a night of horrors in 2007.
On Monday, a retired prison official testified Hayes threatened to kill a prison guard in March, saying he had nothing to lose.
Psychologist Mark Cunningham said Tuesday that Hayes, 47, would likely serve his sentence without seriously hurting an inmate or guard.
He said Hayes had already served 25 years in prison without committing serious violence and that prison violence is more likely with younger offenders.
Inmates killing correction officers are rare, with only one death per every 1 million prisoners, Cunningham testified.
Cunningham said his study of thousands of murder convicts concluded that they were not more likely to commit assaults in prison than inmates serving time for other crimes.
He said jurors and psychiatrists who testify at trials often predict murderers will commit violence in prison, but studies contradict that belief.
"This is a body of research that is very counterintuitive," Cunningham said.
Cunningham said his research in Missouri found that inmates serving life sentences were actually half as likely to be involved in assaults as parole-eligible inmates. He said prisoners serving life sentences might be motivated to avoid making their time tougher by losing privileges.