The South River, New Jersey-born Sicknick had returned to Capitol Police headquarters after the attack when he collapsed and was hospitalized. He died the next day.
The day after the attack, Capitol Police said Sicknick, who joined the force in 2008, “was injured while physically engaging with protesters.”
In a statement on Monday, the Capitol Police said they had accepted the results of the doctor’s office.
“That doesn’t change the fact that Officer Sicknick died on duty and bravely defended Congress and the Capitol,” it said.