At common law, the fleeing felon rule permits the use of force, including deadly force, against an individual who is suspected of a felony and is in clear flight. According to David Caplan "Immediate stopping of the fleeing felon, whether actually or presumably dangerous, was deemed absolutely necessary for the security of the people in a free state, and for maintaining the "public security." ... " Indeed, it has been said that the social policy of the common law in this matter was not only to threaten dangerous felons and hence deter them, but was also to induce them to "surrender peaceably" if they dared commit inherently dangerous felonies, rather than allow them to "escape trial for their crimes." [1]
Goes on to say:
U.S. law
Under U.S. law the fleeing felon rule was limited in 1985 to non-lethal force in most cases by Tennessee v. Garner, 471 U.S. 1. The justices held that deadly force "may not be used unless necessary to prevent the escape and the officer has probable cause to believe that the suspect poses a significant threat of death or serious bodily harm to the officer or others."[2]
A police officer may not seize an unarmed, nondangerous suspect by shooting him dead...however...Where the officer has probable cause to believe that the suspect poses a threat of serious physical harm, either to the officer or to others, it is not constitutionally unreasonable to prevent escape by using deadly force.
Justice Byron White, Tennessee v. Garner[3] Fleeing felons may be followed into places not open to the public without a warrant if the officer is in "hot pursuit[4]." Deadly force that is executed by a co-defendant against an accomplice is not justified by the fleeing felon rule.
Seems like this was very clearly a mistake by the officer. If he was actually just sworn in a matter of hours before the incident I wonder how much his inexperience contributed.
I think you showed clearly how this was not a case of murder with actual law citations. ---