They still congregate, more than two months later, as much to grieve as to try to figure out how Anderson disappeared after a Friday night out - not to be found until the following Monday morning, near a public walkway in a heavily visited tourist town.
While Hunterdon County officials have not yet determined what killed Anderson, his friends from California to Georgia have posted to a Web site dedicated to investigating what they feel certain was a suspicious demise. Their Internet inquiry offers photos of the affable musician and the spillway, with poems he wrote and frequently updated commentary about the case.
The autopsy was inconclusive, said Walter Uhlman, the medical examiner. Police are awaiting toxicology results, which could take weeks or months.
Left without official answers, Anderson's friends have theorized their own:
A jilted lover. A mysterious woman seen peering at funeral goers. A stalker.
Lambertville police have little reason to believe the death was anything but an accident, Detective Michael Bozsolak said.
The body showed no apparent defensive wounds, and Anderson's wallet was intact, suggesting that he was not robbed, Bozsolak said. He says he suspects the toxicology tests will confirm an accidental death.
"The subject had a lot of friends, and a lot of his friends are going out in left field with these stories," he said.
The friends' theories swirl about this Delaware River town - in the club where the free-spirited Anderson played, in the music store where he once worked, and through his network of friends in Upper Bucks County.
The speculation continues on the "Mysterious Case of David Anderson" Web site (http://www.psychicpet.com/mystery/), created in his memory by Bob Coshland, 32, a friend from Palisades High School who now lives in California.
"There are a lot of questions about what happened, and a lot of those questions are really unanswered," Coshland said.
The questions emerged as friends, in town for the funeral, congregated at the spillway, a forceful 15-foot release of water from the canal into a small pool that feeds into the Delaware River.
They waded in the placid pool, stood on the towpath bridge above it, and tossed debris into the water so they could watch how it floated, said Dwight Altier, 32, of Pipersville, another high school friend. They wanted to see for themselves whether Anderson could have just fallen in.
But each time, he said, the currents carried debris way into the river; none was trapped in the pool where Anderson was found.
Also in question is access: The part of the pool where his body lay can only be reached from a darkened parking lot behind a shuttered Acme market.
"The big question is, 'How did he get here?'" Altier said, standing in the lot and staring down the ledge.
Lambertville police reported that Anderson had several facial lacerations of unknown cause.
"There's just a gut feeling everybody has about it," said Adam Baker, 31, a friend.
Friends say they do not need toxicology reports to confirm that Anderson was drunk the night he was last seen.
That night was like many other weekend nights, when Anderson could be found at John & Peter's Place, a favorite bar and music club on Main Street, where he and his current band, 'abe,' performed.
It was misting rain at 3 a.m. when Anderson left the bar, friends recall, headed to Baker's apartment across the bridge in Lambertville to stay the night. He came back to the bar once for his umbrella, but then left and was never seen alive again.
Those who know Anderson say two things are certain: He could not swim. He was afraid of water.
"Whenever you would walk with him along the canal, he would always stay on the far side of the canal, against the hedge," Baker said.
Besides, he had walked there drunk many times before without ever falling in, friends say.
There are generally no murders in Lambertville. State crime statistics have recorded none in the last decade. And there have been no murders in Hunterdon County since 1994, according to Sgt. Al Della Fave of the New Jersey State Police.
Friends say Anderson would be amused at the mystery that has shrouded his death. He was a conspiracy fan - always reading books about Sasquatch and the Loch Ness Monster. Sometimes he joked about staging a fictional monster, "The Deli," in the Delaware.
Living in Georgia and California before settling last January in Delaware Township, N.J., Anderson worked in restaurants, bookstores and music shops to finance his musical career. Friends say he amassed a collection of more than 10,000 records and once offered, in Athens, Ga., to pay his rent with Beatles singles.
The friends he left behind say they can't move forward in grieving his death until they are assured they know its cause.
"I'm not looking for conspiracy," Altier said. "I'm just looking for an answer."
Oshrat Carmiel's e-mail address is email@example.com