Authorities say that a 2-year-old boy found dead in an apartment alongside his father starved to death shortly after his father died from natural causes.

Police discovered David Conde Sr., 59, and his son David Conde Jr.’s lifeless bodies in a bedroom in a “fairly clean and well-kept” upstate New York apartment in February.

Reports show Ontario County Sheriff’s detectives spotted space heaters and initially suspected carbon monoxide poisoning in the home. However, officials said it would take weeks to months for toxicology results. The sheriff’s office announced the findings of the report Monday.

Conde Sr. died because of cardiovascular disease.

“It is believed Mr. Conde passed away first, and the child was not able to obtain any nourishment after his father passed,” the sheriff’s office said in a news release.

Conde Jr. would’ve celebrated his third birthday on Oct. 29, according to his obituary. He was born with a medical condition and had recently learned to walk after several surgeries, casts and rehabilitation. His father had full custody, and the boy’s mother was not part of his life, according to reports.

Conde Sr., a Brooklyn native, shared several photos of his son’s medical journey on social media with warm messages. Neighbors said the pair would spend most of their time in the apartment but would occasionally be seen in and out.

Authorities went to the apartment in Geneva, New York, near Seneca Lake, after receiving a call from a concerned relative on Feb. 15 who had not heard from the father in several days. Ontario County Sheriff’s Lt. David Cirencione said at a February press conference that the father and son had been seen or heard from over seven to 10 days.

“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,” Cirencione said.

Cirencione said there were no signs of forced entry, and the doors were locked from the inside. Building staff had to unlock the doors for the deputies to gain access. There was food and clothes in the home for the child, reports show.

“This has been a tough one for all of us who worked it from day one,” Cirencione reportedly wrote in an email to the Finger Lakes Times on Monday afternoon. “Once we ruled out carbon monoxide, we sadly knew this was a likely cause. This a very, very sad case.”