Two men charged in a series of shootings in the Phoenix area were indicted Wednesday on suspicion of setting two Wal-Mart stores on fire.

Samuel John Dieteman, 30, and Dale S. Hausner, 33, each face two counts of arson in U.S. District Court.

The two fires June 8 gave police a break in the investigation that led to the capture of Hausner and Dieteman in the shootings.

Cameras in one of the stores picked up two men walking through the aisles, followed by smoke. A few weeks later, someone who saw the video on TV told police one of the men looked like Dieteman.

Undercover police followed Dieteman to the apartment he shared with Hausner. After keeping the two men under tight surveillance, police arrested them this month in connection with 16 of the 37 shootings that began in May 2005.

Both are charged with two counts of murder and 14 counts of attempted murder as part of the shooting spree.

Dieteman's lawyer, Maria Schaffer, would not comment Wednesday. Hausner's lawyer did not return a call.