A Burnsville father accused of inflicting fatal injuries on his newborn son has been charged with three counts of second-degree murder.

Michael A. Herkal, 32, faced upgraded charges in Dakota County District Court on Thursday related to the death of his 13-day-old baby. The child, Anthony Herkal, remained on life support for two days before dying from massive brain injuries Aug. 14. An autopsy revealed that he had two skull fractures.

According to the charges, Michael Herkal initially told police that his 2-year-old son pulled the infant down from the couch twice within 10 minutes. Then, Herkal later claimed he squeezed the wriggling baby while changing his diaper and that the child had “slipped out of his hands” and fell onto a coffee table.

Investigators found internet searches on Herkal’s cellphone that included, “someone threw a baby on the floor,” “baby breathing hard,” “noisy baby breathing: what’s normal and what’s not.”

The infant’s mother, Jamie Keener, was not at her Apple Valley home when the baby was injured. She returned home after work and called 911 after finding the child unresponsive.

While the newborn was on life support, Herkal was charged with first-degree assault and malicious punishment of a child. Prosecutors vowed to issue additional charges should the baby die.

Herkal’s criminal history in Minnesota includes four convictions for violating domestic abuse no-contact orders, five for drug possession, and one each for check forgery, harassment and disorderly conduct.

He remains jailed in lieu of $750,000 bail.