While intoxicated, during a fight with his to-be-ex-wife, Tim Russell assaults his wife, rips the telephone wire out of the wall, tells his wife not to call the cops, and leaves the premises. His wife (smartly) goes next door and calls the police, and Russell returns to the home shortly thereafter with a gun. Finding only his children and his sister-in-law still at the house, he orders them to leave, and they do so. The police then arrive. At which point Russell shoots the first two officers who arrive, who never know what's coming -- they still have their pistols in their holster.
Russell has no prior criminal record. His first penalty phase ends in a mistrial. His second results in a death sentence. The California Supreme Court unanimously affirms.
Tough to say that this case is any worse than your typical murder-of-police-officers case. So you've got the traditional problem of rationally deciding which cases are truly death-deserving.
But the reality is that if you deliberately shoot a police officer, you're exceptionally likely to be sentenced to death. De jure possible. De facto virtually certain.