In Sheriff Clarence Dupnik’s press conference tonight, he said that law enforcement are “actively in pursuit” of a second suspect in the shooting of 19 people, including Rep. Gabrielle Giffords, in Tuscon Arizona today. Six people were killed, including Judge John Roll, Rep. Giffords’ Community Outreach Director Gabe Zimmerman, and a 9 year old girl.

Dupnik would not name the key suspect in the case, but other outlets have identified him as Jared Loughner, a 22 year-old Tuscon resident who had been a student at Pima Community College. But Dupnik did say that the man had been the “subject of police interest” recently, when he had threatened “to kill” someone — though not Rep. Giffords.

The Sheriff’s office believes the second suspect arrived at the location of the shooting with Loughner, and Dupnik indicated that they have pictures of him. Dupnik confirmed in the press conference that the second suspect is a white male, in his 50s, and they do not believe he took part in the shooting.

“We have an individual that we are actively in pursuit of, but I can’t tell you who he is at this point,” said Dupnik. “Don’t know where he’s headed, don’t know who he is.”

Dupnik was asked whether there was footage of the shooting taken by the mall, but he refused to answer.  If so, it would explain how law enforcement officials had images of a second suspect.