In one picture, Amber is shown walking with Connor Gibson side by side as they head to the Hamilton park where he was to batter the 16-year-old, sexually assault her and strangle her.
Video footage shows Gibson then walking home to the Blue Triangle homeless accommodation following the crime.
At one point he pretends to stretch against a fence, appearing to be hiding his face from a passing car.
Another clip, released by the Crown Office following a guilty verdict delivered at the High Court in Glasgow, shows the murderer walking with clothing used in evidence against him and then disposing of it.
Gibson denied the charges against him but was convicted of killing his little sister following a 13 day trial.
Another accused, Stephen Corrigan, 45, was found guilty of attempting to defeat the ends of justice by intimately touching and concealing Amber’s body after discovering her at some point in the two days after her death.
The 20-year-old – who also uses the name Niven – was arrested on December 1.
The day before his arrest he posted on Facebook: “Amber, you will fly high for the rest of time. We will all miss you. Especially me. I love you ginger midget. GBFN (goodbye for now) X”.
At the time of Amber’s murder, Gibson was living at the Blue Triangle homeless hostel in Hamilton while Amber was at the town’s Hillhouse children’s home.