The sole suspect in the triple homicide at a UPS facility in San Francisco last week, 38-year-old Jimmy Lam, remains a bit of a mystery to investigators, and at a press conference Friday afternoon the SFPD said they still do not have a motive in the shooting. But they did release a photo of Lam, who shot himself at the scene just as police were arriving — and apparently they have body camera image of that terrible moment as well, though that has not been released.

As the Examiner reports, Lam was carrying two stolen guns with him last Thursday morning at the Potrero Hill warehouse, a MAC-10 with an illegal 30-round clip, which he used in the killing, and the automatic pistol he used to kill himself. One gun was stolen in Napa, and the other in Utah, and it's unclear how Lam obtained them.

Per the Associated Press, Commander Greg McEachern said that while they have not established Lam's exact motive, "the shooting appeared purposeful and targeted." As we learned earlier, Lam arrived at a regular 9 a.m. meeting of drivers and specifically targeted three drivers, chasing one, Mike Lefiti, out into a parking lot. All three victims, including Wayne Chan, 56, and Benson Louie, 50, had worked alongside Lam for many years, and so far no coworkers have suggested that Lam had a specific reason to have animus against them.

Police continue to review a journal retrieved from Lam's Richmond District apartment, as well as his computer.

We learned last week that Lam had been arrested in both 2010 and 2013 on DUI charges, but that was the extent of his criminal history as far as we know.

Related: UPS Shooting Suspect Described As 'Loner'; All Three Victims Identified