In the second break-in in two months, a man stole a gold- and quartz-lined box from a display case in the Oakland Museum that is rumored to be worth $800,000. The box dates to the 1800s and was a gift from a Gold Rush pioneer to his wife, and it's belonged to the museum since the 1960s.

Another break-in in the same gallery at the museum in November resulted in the theft of several gold nuggets and other items.

A source has explained to SFist that while the museum has security cameras and guards on site, the guards actually would not leave their surveillance room during the November incident and are only contractually obligated to call police when they witness a break-in.

There is surveillance footage of Monday's break-in as well, and police say the suspect is an African-American male about 5 ft. 9 in. to 6 feet tall, but he was wearing a mask at the time.