Nine months ago, a 2-year-old and his father were found dead in their New York apartment. Now, authorities have determined what caused their deaths, People reports.

The Ontario County Sheriff’s Office announced this week that 59-year-old David Conde Sr. suffered from a cardiovascular disease. According to The New York Post, he died of natural causes as a result of his condition. David Conde Jr., his son, died some time later due to malnourishment. His death was ruled an accident, People reports.

Their bodies were found on Feb. 15, and they were they were last seen alive on Jan. 22.

“It is believed that Mr. Conde passed away first, and the child was not able to obtain any nourishment after his father passed,” police said.

According to The New York Post, Conde’s family called the police after they hadn’t heard from the 59-year-old for over a week. Officers noted their were no signs of struggle in the residence, which according to Ontario County Sheriff’s Lt. David Cirencione, led them to believe that no one “else was in the apartment when these two passed away,” the Democrat & Chronicle reports.

“We want to do everything we can to get answers for the family so they can get closure,” Cirencione said. “It was a very difficult scene for us to work, for all the first responders that had to go in there. This isn’t something we see every day. It’s not pleasant. It was a very disturbing scene.”

What happened to the Conde’s became clearer after experts determined they didn’t pass from carbon monoxide poisoning.

“Once we ruled out carbon monoxide [as the cause of death], we sadly knew this was a likely cause,” Cirencione told the Finger Lakes Times. “This is a very, very sad case.”

According to the Democrat & Chronicle, Conde Sr. acquired full custody of his son soon after he was born. His mom appeared to not be in his life. The toddler’s obituary shared that he was born with a medical condition and had just “recently learned to walk, following many surgeries and months of casts and rehabilitation.”

It also described Conde Jr. as “a beautiful baby boy with curly locks, that had a determined smile and sweet disposition.”