Prosecutors: Man already charged in 2 killings now charged in February slaying

Prosecutors say a man from New Jersey, already accused of having killed his ex-girlfriend's grandmother and brother -- and live-streaming his own police chase -- has now been charged in a slaying in February.
According to the Burlington County prosecutor, Terrance Matthews, 23, is accused of firing at two men in a car on Feb. 18 in Willingboro.
The prosecutor says Davell Williamson, 21, was killed and the other man was wounded.
On Friday, prosecutors announced Matthews had been charged with killing Jennifer Vassell, 68, and her grandson, 9-year-old Ishon Mathiln Jr.
Authorities said both were stabbed multiple times, and the boy appeared to have been drowned in a bathtub.
Authorities say Matthews live-streamed the high-speed police chase on Facebook before crashing Thursday.
It's unclear whether he has an attorney.
AP wire services helped contribute to this report.