By Ian Bush

PHILADELPHIA (CBS) — A Philadelphia man is behind bars, charged in the stabbing deaths last month of a woman and their unborn child.

While her mom was being attacked, Eboney White’s 12-year-old daughter locked herself in the bathroom and bravely called 9-1-1.

It was in that Elkins Park apartment where the Montgomery County District Attorney says Tristian Jones used a paring knife he’d bought hours earlier to end White’s life.

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White was seven-and-a-half months pregnant with their son. The fetus did not survive; the death, also ruled a homicide.

Jones is married to someone else, and investigators say the 35-year-old admits his wife did not know about his extracurricular activities.

The first-degree murder charges do not allow for bail, so Jones is being held as he awaits a preliminary hearing scheduled for March 29.