Police arrested another Toronto man on Tuesday in connection with the death of Ming-Chien (Teresa) Hsin earlier this year.
Justine Ordonio, 25, was charged with first-degree murder.
On Monday, Peel police arrested 21-year-old Mark Dookhram as a result of the same investigation.
The 59-year-old woman's body was found inside a black BMW with "obvious signs of trauma" in the Robert Speck Parkway and Hurontario Street area in Mississauga on April 10.
Hsin, who was the owner of a chain of spas, had survived a stabbing in November 2014 outside of her townhouse. Police say they are still investigating and can't confirm if the two attacks are connected.
Ordonio is scheduled to appear in court on Wednesday.