A jury at Chelmsford Crown Court found former builder Paul Taylor, 60, guilty of murder after 23 hours of deliberation.
He was found guilty of three counts of rape, one attempted rape and a serious sexual assault, which were all committed in the months leading up to Miss McGrath's murder.
Mr Justice Owen told Taylor:
"You have finally been brought to justice and you will now serve life in prison."
Taylor is due to be sentenced tomorrow.
For more on this story see the ITV Anglia website.
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Patchy rain Sunday morning.