Three Doherty students were off campus during lunch and got into a "confrontation" with at least two people in a auto in the parking lot of a business in the 4600 block of Austin Bluffs Parkway, police said.
Police said that Murphy was across the street watching the white Ford Explorer burn. The father began to fight with Murphy until he was able to detain him in the garage until police arrived on scene. He said he purchased the knife at a Walmart several months ago, according to the affidavit.
In a police document, Malik Murphy revealed he often had "homicidal ideations", and planned to kill his family and bury them in the backyard so he could be alone at the home.
The 19-year-old and his younger siblings all slept in the same room.
Murphy now faces two counts of first-degree murder. Murphy is accused of stabbing the young kids to death in the family home. Black said they called 911 while the attack was unfolding.
Roy Dotrice, 'Amadeus' and 'Game of Thrones' actor, dead at 94
He performed in various movies including Oscar-winning film Amadeus , in which he played the role of Leopold Mozart. They had three daughters together - Yvette, Karen and Michele, actors all.
Police are not looking for anybody else in connection with the crime. "It's very, very hard for our staff", Black said.
19-year-old Malik Murphy appeared before an El Paso County judge for the first time Wednesday to hear what charges he's being held on.
A vigil was held for the two children at 6 p.m. Tuesday in Flanagan Park.
He was arrested and charged with arson and criminal damage to property, Cromwell Radio Inc reports.