I heard about this. The police say they thought he had a gun in his hand, but actually all he had was a phone in his pocket.
They don't say that they just say they thought he was holding "something" they never mention that they thought it was a gun, or a knife or any kind of weapon.
In the article I saw they did:
When officers arrived, Loxas had returned to his house, but came to the door with the baby in his arms, police said. Peters and another officer told investigators that they saw a black object in Loxas' hand. Loxas turned to go back inside when Peters, who was standing 18 feet away at the edge of the driveway, shot him in the head with his patrol rifle, police said.http://www.azcentral.com/news/articles/2012/02/15/20120215shooting-seventh-scottsdale-police-officer.html#ixzz1mZ1VZrTu
"(Loxas) was holding the baby in his left arm in front of his upper body and face. Moments later, he reached down to his right, lowering the baby, clearly exposing his head and upper body. Officer Peters responded to the movement with a single shot (to) the suspect's head. The suspect fell to the ground and the baby was rescued by officers. The suspect died instantly," Clark said.
Peters "felt he had to prevent him from re-entering the house," Clark said. "The intent was to rescue the baby." Investigators later determined that Loxas was not carrying a gun but had a cellphone in his pants pocket.