After more than 20 hours of searching, it was the discovery rescuers were dreading.
"It's always sad to have it turn out the way it did we were hopeful early on that perhaps he would have been able to make it back to the shoreline," Dep. Inspector Harold Jantzen from the Suffolk County Police Department said.
What is likely the 41-year-old's body was first spotted by a passing boater about a mile from where Luca's 5-year-old son was rescued by a Good Samaritan Friday afternoon.
"Turns out he was five, he was wearing a life jacket, and he had a whistle, so he was well provisioned for being out on the water. So we said, 'Where did you come from?' He said he was with his dad. And I said, 'Where is your dad now?' And he said, 'My dad went under,'" rescuer Ted Sandomenico said.
The boy went under after somehow falling overboard from his inflatable kayak.
Luca's son survived, kept afloat for at least 30 minutes by a life jacket.
"We're really happy and thankful his boy was wearing a lifejacket. This could have been two lives instead of one," said U.S. Coast Guard Petty Officer Erik Swanson.
That one life lost is now being honored.
Luca served with the NYPD for 21 years, working in its recruitment section.
Mayor Michael Bloomberg issued a statement that reads, "The NYPD and the entire city suffered a tragic loss today with the death of one of our finest, Police Officer Patrick Luca. My heart and prayers go out to Officer Luca's wife and children, loved ones and friends, and I want to offer condolences on behalf of a city grateful for his service and dedication to protecting New Yorkers. We thank the Suffolk County police for their help in the search and we owe a tremendous debt of gratitude to the boaters who rescued Officer Luca's son."
Luca was from Smithtown.