California police share video of person of interest in 6 murders: "We do believe we could have a potential serial killer"

The fatal shootings of six men in California have been linked using ballistics tests and video footage, and police said during a Tuesday press conference that they are looking for a person of interest. 

"We do believe we could have a potential serial killer," Stockton Police Chief Stanley McFadden said. "That's how we're going to treat it as such."

The person of interest appears on video at several of the crime scenes — but no evidence directly links them to the shootings, McFadden said. Additionally, authorities do not know whether there is one suspect or multiple.