While working to convert an old hospital in Fort Mason to housing in 2010, maintenance crews made a mysterious discovery. Digging around soil surrounding the building, crews uncovered human bones from about 20 people, as SFist reported at the time, along with a bottle of hair tonic.

These days, KTVU reports that archeologists have new theories, more details, and a clearer timeline for the site. "It was a hospital from the 1860's and basically we found a large pit, it's called an ossuary pit," National Park Service archaeologist Leo Barker tells the channel of the bone-filled pit. There, some 1,400 bones were stacked by body part, with no complete skeleton from any one individual. That dating to the 19th century comes from medicine bottles found near the site.

Barker now believes that one Dr. Edwin Bentley, a doctor at what was then called Point San Jose, had collected the bones as a teaching tool. "They seem to be related to teaching," said Barker, "they seem to be related to examinations that took place for determining cause of death."

Barker's theory is that when the building changed hands, new doctors simply buried the old bones. But here's one weird, ambiguous quote from Barker: "The next set of surgeons was not interested in maintaining these curio cabinets that were the result of education and other activities." What were those "other activities?" Perhaps they'll be revealed in time as analysis of the bones and other materials from the pit continues, hopefully to be made available online.