Paul Taylor, of Valentine Close, Fareham, Hampshire, was also found guilty of three rapes, an attempted rape and a serious sexual offence.
Today, at Chelmsford Crown Court, Judge Mr Justice Owen said: "I think it is clear there was a sexual element to the murder of Sally McGrath.
"The evidence revealed a pattern of behaviour in which you lured your victims in under the pretence of giving them a lift home.
"You then drove them to a rural or isolated area and forced yourself upon them.
"Your predatory sexual attacks took place over 30 years ago but your victims have been left scarred for life.
"I have no doubt the brutal murder of Sally McGrath followed the same pattern and resulted from her resistance to your sexual demands."
More top news
Cambridgeshire's Hannah Macleod has been named in the 16-strong hockey squad to head to Rio this summer.
The national newspapers have been reacting to England's exit from Euro 2016 after they were beaten 2-1 by lowly Iceland.
Sunny spells at first this morning but it will turn cloudy through the day and rain will arrive during the afternoon. Highs of 18ºC.