Passing sentence, Mr Justice Griffith Williams told Sharp: "This is a horrific, cold hearted murder, carried out to gratify your perverted sexual desires."
Sharp, dressed in grey jogging bottoms and a grey jumper, made no reaction but the victim's sister, Emma, sat in the public gallery just yards from the dock, did not take her eyes off the defendant throughout the 50 minute hearing.
More top news
Manchester United footballers paused before training today to hold a minute's silence for victims of the suicide attack at Manchester Arena.
Stephen Jones described how he rushed to help severely wounded children in the aftermath of the Manchester Arena bomb attack.
Saffie Roussos, believed to be eight years old, was described as a "beautiful little girl".