More than a decade before Joshua Komisarjevsky committed one of Connecticut’s most gruesome crimes, he harbored homicidal thoughts about his devoutly religious father and got tattoos — two upside-down crosses and a marking declaring that Jesus was dead, it was revealed yesterday.

Komisarjevsky, 31, was hospitalized at 15 after torching a vacant gas station. But instead of putting him on Prozac, as recommended, his parents sent him to a religious residential treatment program, according to evidence presented in New Haven Superior Court.

His parents testified in hope that the jury spares him the death penalty for killing Jennifer Hawke-Petit and her daughters, 17 and 11 years old, and sexually abusing the younger girl in their Cheshire, Conn., home in 2007.

Komisarjevsky’s attorneys said his parents also opposed counseling and medication after learning that their son had been sexually abused for years by a foster teen they had taken into their home.

Prosecutors countered by citing Komisarjevsky’s prior convictions for 19 nighttime residential burglaries and noting that an earlier judge had called him “a calculating coldblooded predator.”