Last week, the police in Stockton, California, warned of homicides that may have a pattern. At the time, they did not classify it as a serial killer. But NBC News reported that on Friday, Stockton police chief Stanley McFadden said, “By definition, you could probably very well call this serial killings.”

Unsolved homicides in Stockton: What do we know?

Five of the victims’ names have been released, according to ABC News: “Paul Yaw, 35, was killed on July 8; Salvador Debudey Jr., 43, died on Aug. 11; Jonathan Hernandez Rodriguez, 21, was killed on Aug. 30; Juan Cruz, 52, was the Sept. 21 victim; and Lawrence Lopez Sr., 54, was slain on Sept. 27.”

The New York Times reported on Monday that the Stockton Police Department believes that seven total murders are connected to this apparent serial killer.

In connection with the murders, the Stockton Police Department released a photo of a person of interest. The investigation is still in the early stages and much is still unknown.

The killings were linked together because of patterns that emerged in the investigation. The Guardian reported that none of these victims were robbed or appeared to be beaten before they were killed and that all of the killings happened within the radius of a few square miles.

Details about the investigation are still forthcoming.