Alex Hidalgo, 37, of Ogden, is accused of murdering his son on Friday while the child's mother was out running errands

A Utah man said he killed his 10-month-old son by stabbing him on a homemade altar after he found 666 'devil mark' on his body.

Alex Hidalgo, 37, of Ogden, is accused of murdering his son on Friday while the child's mother was out running errands.

When the woman returned, she found Hidalgo sitting on the couch, reading a Bible and watching a religious video.

He said the baby was dead and told her not to call anyone or he would be sent to prison, according to court documents.

She then found her son's body inside a plastic garbage bag stashed in a closet and alerted a neighbor.

While she gave the baby CPR, Hidalgo fled and broke into an abandoned home, where he was arrested on Saturday wearing bloodstained clothes - the same outfit police believe he had on when he murdered his son.

When the woman returned to the apartment (pictured), she found Hidalgo sitting on the couch, reading a Bible and watching a religious video

Hidalogo is being held without bond at the Weber County Jail on suspicion of felony charges of aggravated murder, abuse or desecration of a dead human body and obstruction of justice.

The Utah Medical Examiner's Office said an autopsy showed the child had three penetrating stab wounds to the neck including one that severed the carotid artery and the jugular vein.

The baby was given CPR by his mother and a neighbor but was pronounced dead in hospital.

Police investigators reported finding blood splatter in the apartment and a paring knife in the kitchen sink.