The homeless man who was beaten to death by a group of three men had over a thousand dollars on his person, a San Francisco Police Department investigator says, making it clear that robbery was never a motive behind the attack. Police are also saying that they have physical evidence that could make this case a slam dunk — that is, if they ever find the suspects.

It's likely that you already know the terrible tale. But, to recap, 67-year-old homeless man Tai Lam was beaten to death as he slept in an alley near Sutter and Montgomery Streets late the night of Sunday, November 23. Surveillance footage in the area (only some of which has been released by police, as video of the beating itself was deemed too violent for public viewing) shows a group of three men who stomped, and kicked him to death over two beating sessions between 11 p.m. and midnight.

Here's some video of the suspects taking a smoke break before they attacked the sleeping man:

Police held a press conference Tuesday in which they released additional details of the attack (you can read SFist's report on that here), but today the Chron's CW Nevius has some additional information on the crime, straight from the lead investigator on the case, SFPD Sergeant John Cagney.

Cagney tells Nevius that Lam "had a substantial amount of money on him...over $1,000," making the fatal beating what Nevius terms a "thrill kill."

So why was Lam, who used crutches to get around after a long-ago bout with polio, sleeping outdoors? That's unclear, Nevius reports, saying that family members had tried to "tried to help (Lam) out, they said, opened up their houses to him, but Lam had declined."

However, Lam was never aggressive or troublesome, and, according to Cagney "was very clean and never caused any problems. All who knew him said he was a very respectful gentleman."

In fact, he was was so fastidious that he "made it a point to urinate in plastic bottles so he wouldn’t soil the alley where he slept," Nevius reports.

Then there's the suspects. Police said Tuesday that they believe that the men who killed Lam had taken BART or Muni to and from the location, likely using the Montgomery Station.

Nevius reports that police believe the men attended the November 23 Flask Mob photo walk, described on the event's Facebook page as "a monthly San Francisco meetup. This is an outlet for us as creative individuals, to express ourselves."

According to SFist commenter thetens "One of the guys who started Flask Mob said on Twitter that SFPD contacted them asking for photos, told them they knew the men weren't part of the event, but were around it," an assertion confirmed by Cagney, who tells Nevius that "the group’s organizers have been 'super helpful.'"

So police likely have photos from the Flask Mob, the surveillance footage, and evidence from the crime scene, itself.

"'Our ace in the hole is that we have physical evidence,' Cagney said. He wouldn’t say what it was, but he did say it could make the case," Nevius reports.

All that said, police are still eager for more information, "anything to help us get these guys" a police spokesperson told SFist today. If you have any information, at all, you're urged to contact Cagney at 415-734-3181 or by email at [email protected] If you prefer to remain anonymous, contact SFPD via their anonymous tip line at 415-575-4444 or send a tip by text message to TIP411 with “SFPD” in the message.