Updated

A Utah judge denied bond to a young father accused of plotting for a month before killing his infant son with a rifle.

Joshua Petersen, of American Fork, will stay locked up until formal charges are filed Friday.

Utah County prosecutor Craig Johnson says a police sergeant testified Monday that the 21-year-old planned for a month to shoot his 5-month-old son and did so last Friday.

Johnson tells The Associated Press the motive for the shooting at a home is unclear.

Family members tell Utah news outlets that Petersen was suffering from depression and the recent breakup of his relationship with the boy's mother.

Police say Petersen sought to turn the gun on himself after killing his son but was stopped by a family member.