She was abducted some time after and killed. Her body was found dumped on the Metn highway several miles away.
Police sources told the Telegraph the first autopsy revealed the cause of death as strangulation, however a second postmortem examination is to be carried out later.
They said they did not believe the attack to be politically motivated.
One friend told the Telegraph: "It's horrific. We had no idea what happened to her until we got a call today to go to the police station to give statements."
Miss Dykes had been working in Beirut as the programme and policy manager for the Department for International Development since January 2017. Sky more