Detectives investigating the death of a man who staggered into a Stoney Creek Mountain gas station covered in blood last Friday say they believe a trio of teen sex workers were trying to rob the man when things "escalated."

A third 17-year-old girl was arrested in connection with the case in Toronto today, police say. Two others turned themselves in earlier this week.

"Investigators believe that the three accused females were attempting to rob the victim and the situation escalated," a police news release reads.

"As this matter is now before the courts, there will be no further information released."

The identity of the three teens cannot be released because they are protected under the youth criminal justice act.

The victim, 33-year-old Hayder Qasim-Rushdi, first appeared at a gas station on Upper Centennial Parkway near Green Mountain Road just after 2:30 a.m. last Friday.

He died two days later in hospital.

Police believe the three girls were working as escorts and Qasim-Rushdi was a client of theirs.

Investigators say the teens drove with the man to Hamilton last week and stabbed him in "a rural property not too far from the gas station."