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Josh Petersen, 21, of American Fork, was booked into the Utah County Jail for investigation of aggravated murder in the shooting death of his 5-month-old son Friday, April 5, 2013.

AMERICAN FORK — A 21-year-old father accused of shooting his 5-month-old son in the head with a rifle has been officially charged.

Joshua David Petersen was charged with aggravated murder, a first-degree felony, in Provo's 4th District Court on Friday.

Prosecutors say Petersen had been planning to shoot his son, Ryker, for about a month, and went through with it April 5 when he placed the infant on a couch and shot him with a .22 caliber rifle.

Police believe Petersen was then about to shoot himself when a family member stopped him.

On April 8, a judge ordered Petersen held without bail at the Utah County Jail while charges were pending.

Petersen's next scheduled court hearing is Monday.

Pat Reavy, Twitter: DNewsCrimeTeam