The Brief Prince George's County Police have arrested the woman accused of stabbing her grandmother to death over the weekend. Breante Thomas has been charged with first and second-degree murder for allegedly killing Helen Thomas. Police in Prince George's County have arrested the woman accused of killing her grandmother over the weekend. She is accused of stabbing and killing her 81-year-old grandmother, Helen Thomas on Sunday, Sept. 14, and stabbing another family member. What we don't know:Officials did not identify the second family member who was stabbed.