A Framingham man found dead near Lake Tashmoo last week either jumped or fell from a Steamship Authority ferry, police said.

Francis G. Elms, 74, of Framingham, was found fully clothed in the ocean west of the Lake Tashmoo opening by a caretaker on the morning of Sept. 25, according to state police Sgt. Jeffrey Stone. A state medical examiner has determined that the cause of death was drowning, Sergeant Stone said.

Mr. Elms had severe medical problems, Sergeant Stone said, including Parkinson’s disease and dementia. He said Mr. Elms left his house in Framingham on Sept. 24 and rented a car after not having driven for a year because of declining health.

Police have determined that Mr. Elms parked his car at the Palmer avenue Steamship Authority lot and boarded the noon ferry to Oak Bluffs that day. During the trip, Sergeant Stone said, some witnesses saw him put his leg over the railing. Members of the crew talked to him, he said, and Mr. Elms assured them he was fine.

Steamship Authority general manager Wayne Lamson said the crew at the time didn’t feel there was a threat or the need to call local authorities.

Mr. Elms got off the boat and went to the Lookout Tavern, Sergeant Stone said, and then boarded the 2:45 p.m. ferry leaving the Island. The boat was the freight ferry Katama, and police say it now appears that Mr. Elms drowned after either jumping or falling into the ocean from the ferry.

“We are surmising that he either fell or jumped,” Sergeant Stone said. “We’ll

never know which one.”

However, he noted that Mr. Elms had problems with his balance. “We surmise that he fell off the Katama,” the police sergeant said.

Mr. Lamson said yesterday that the boat line normally counts the number of people and cars that board a ferry, but does not count those leaving. During the investigation that followed the death, he said, someone reported seeing Mr. Elms purchase a ticket to leave the Vineyard at the Oak Bluffs ferry terminal. The Steamship Authority reviewed security camera footage from the 2:45 p.m. Katama trip and determined that while 15 people got on the ferry, 14 people were seen disembarking in Woods Hole. “We’ve just been assisting state police in their investigation to try to figure out what’s happened,” Mr. Lamson said, adding that security camera footage did not pick up anything unusual. The Katama has an open car deck. Mr. Lamson said he didn’t know how someone could fall off the freight ferry, which has high walls and a net along the stern. He added that on that trip, vehicles on the boat were facing both directions. “I don’t know if anybody saw anything,” the general manager said. “No witnesses have come forward at this point.”

He said the Steamship Authority is cooperating with state police “to the fullest extent,” and trying to gather whatever information possible.

Sergeant Stone said the tides that day would have placed Mr. Elms on the north shore, which is where his body was found.

Last week, Sergeant Stone said Mr. Elms came to the Vineyard for his honeymoon in 1967, but it was not clear why he came to the Island Tuesday.

“His family had no idea why he came to the Vineyard,” he said. “It was not a scheduled trip.”

Sergeant Stone said the investigation is now closed.

An obituary for Mr. Elms is published on the website for the Chesmore Funeral Home in Holliston. According to the obituary, he was involved in organizations including the Special Olympics and Cub Scouts, and he volunteered to work with veterans and at the Fatima Shrine. He is survived by two children and his wife. Services were held Oct. 1 in Holliston.