ST. TAMMANY PARISH -- The death of an infant who died in 2016 at 4 months old has been reclassified from natural to undetermined, the St. Tammany Parish coroner said Monday.

The review of the death of Tanner Nauck came after his father was arrested last week in connection with the beating death of 7-month-old Carter Nauck.

Corey Nauck, 25, was booked with first-degree murder after Carter was found to have died of blunt force trauma.

Authorities reviewed Tanner’s death after his father was arrested.

"We completed the review of the case, including consultation with the pathologist who performed the autopsy on Tanner Nauck more than two years ago," coroner Dr. Charles Preston said in a prepared statement. "The reclassification is undetermined for both cause and manner of death."

Tanner Nauck died Jan. 4, 2016. An autopsy found severe congenital heart disease and no obvious signs of trauma, Preston said.

"I would stress that there is no particular red flag after reviewing the case, but given the additional information regarding Carter's death, we are looking at Tanner's death through a different lens," he said. “The mechanism to change a death certificate involves writing a letter to the state. That letter is now in the mail.”