PHOENIX -- Police have arrested another suspect and named an additional one in an armed robbery that culminated in the shooting of a Phoenix police officer on New Year's Eve.
Jason Beau Keep was arrested Friday and charged with conspiracy to commit armed robbery.
The new suspect, 30-year-old William Herbert Mayes, is described as being a black male. His image is also being posted on numerous Silent Witness billboards around the Valley.
Officer Scott Sefranka, a seven-year veteran of the Phoenix Police Department, was allegedly shot by Roger Allen Sharp, 26, in a Walgreens parking lot near 56th Street and Thomas on Tuesday.
Sharp and another man, 36-year-old David Lee Murray, were involved in a crash after they allegedly robbed a nearby business at gunpoint. Sefranka was following them at the time.
After the crash, one officer had Sharp at gunpoint but the two began to struggle, police said. An off-duty Maricopa County Sheriff's Office posse member, who was driving the other vehicle involved in the crash, tried to help.
"Ultimately, Sharp was able to take control of the officer's gun, and he used it to shoot both the officer and the man who came to his aid," Sgt. Tommy Thompson said in a news release.
Police said Sharp and Murray ran into a neighborhood, where they were captured. Scottsdale police also recovered a handgun that is believed to belong to the wounded officer.
Police said Sefranka was showing signs of improvement on Friday. There was no update on the man who came to Sefranka's aid.
Anyone with information on the shooting or Mayes' whereabouts is asked to contact the Phoenix Police Department Violent Crimes Bureau at (602) 262-6141 or Silent Witness at (480) WITNESS, (480) TESTIGO for Spanish speakers.