Volunteer divers who travel the globe seeking missing persons whose remains are believed to be in vehicles underwater discovered the first of several cars they are searching for on Long Island.

William McIntosh, 54, of West Kingston, Rhode Island, and his partner, who would only identify himself as "Diver Dan" from Sydney, Australia, located a sunken vehicle at Cedar Beach in Mount Sinai on Monday evening that they believe contained the remains of a missing person.

The volunteer searchers found a bone inside the vehicle and called 911, Suffolk County police Det. Lt. Kevin Beyrer said Tuesday afternoon. Beyrer said members of the Suffolk police Marine Bureau recovered more human remains inside the barnacle-covered white PT Cruiser, which police pulled out of the water just after 2 p.m. Tuesday.

"There is a missing person who we suspect this driver to be," Beyrer said. "We made a courtesy notification to the family, but we have not definitively made any sort of identification. ... That person had been missing for a number of years."

Beyrer, the commanding officer of the Homicide Squad, said police "believe the vehicle description matches, and we have some items that we recovered that we believe match" the suspected missing person.

The remains would be delivered to the medical examiner's office for positive identification, which Beyrer said "should be pretty quick," but "probably not today."

While at the beach Tuesday, before addressing the media, Beyrer approached a woman who identified herself to Newsday as a relative of the person whose remains she believed would be in the car. She was escorted under yellow police tape and into the crime scene.

McIntosh and his partner would not discuss who they were seeking at the beach, as they said they want police to positively identify the remains before they speak publicly. However, McIntosh said he spoke with the suspected missing person's wife at the scene Tuesday.

"She was appreciative," McIntosh said. He added that his team learned of her husband through her Facebook post.

"She had come here, she said, every day when she went searching for him," McIntosh said. "This was the place that he always would go. He would sit here all the time and watch the birds."

McIntosh and his partner will spend the next several months looking for sunken vehicles they hope contain the remains of 50 people across the East Coast, including several on Long Island, they said. They planned to head to the Valley Stream area for a search Wednesday.

The Cedar Beach discovery marked their third on this latest endeavor and McIntosh’s 16th since a missing persons case in his home state four years ago inspired him to volunteer with a similar organization, the Oregon-based Adventures With Purpose, before forming his own nonprofit in Rhode Island, called Exploring With A Mission, to help loved ones find closure. McIntosh said Adventures With Purpose is sponsoring Exploring With A Mission’s efforts on Long Island.

"When you find a person, you bring them home and you're able to close a chapter in another person’s life, a family’s life," McIntosh said. "We give them hope. If we don’t find a person, just the fact that we’re out there looking for them gives them hope that they will be found."