The police officer who shot Walter Scott radioed in to claim that Scott had "grabbed my Taser", six seconds after firing his final shot, despite video suggesting the unarmed man was not in possession of the stun gun at any point, a Guardian analysis has shown.

Syncing police scanner audio with a shocking video – the eyewitness footage out of South Carolina which led to officer Michael Slager being charged with murder – raises further questions about whether either of two officers on the video performed any CPR on Scott as was previously claimed by police.

Analysis of the police radio shows Slager, the officer who shot at Scott eight times, making the radio call announcing the shots and alleging the Taser seizure, sounding frantic and breathless at the same time as he walks slowly towards Scott's body.

"Shots fired. Subject is down. He grabbed my Taser," the scanner audio from Slager states.

Officer Michael Slager dispatch audio from the Walter Scott shooting.

He reaches the body, handcuffs Scott who has his head down to the floor and walks back to the area where it appears an object was dropped and picks up an item from the ground.

At this point a second officer, now identified as Clarence Habersham, arrives on the scene and radios in. Slager then walks back towards the body and radios in stating: "I need to secure my vehicle". At this point – over a minute after the last shot is fired – neither officer appears to have performed CPR on Scott.

Slager then walks and drops the item, which some have speculated is a Taser, next to Scott's body.