Police say 42-year-old Herman Derico shot and killed his girlfriend, 28-year-old Amy Derosby, Amy's sister, 30-year-old Amanda Bragg, Amanda's boyfriend, 29-year-old Michael Muzzerolle, and then turned the gun on himself. All four shared a house on Belgrade Road in Oakland.
"They were both good girls, and Mike was a good man," said family friend Tawni Lively.
She said very little is known about Derosby's live-in boyfriend, and he may have gone by a different name.
Neighbors, who say they knew him as Khalil, recall hearing an argument before the gunfire.
"There are reports that he screamed out 'You don't know me. You don't know who I really am,'" said Lively. "That concerns everybody."
As family and friends wait for answers from investigators, their focus turns to Amanda and Michael's three-year-old daughter, Arrianna, who was in the house at the time of the shootings. She is the only survivor, and Lively said she witnessed everything.
"She's going to need psychological help," said Lively, "and I want her to have a decent future."
That's why Lively has set up a Go Fund Me page, with the goal of raising $20,000 for Bragg and Derosby's mother, who is now taking care of Arrianna.
Lively said the young girl needs everything from new toys, clothes, and a bed, because all of her belongings are now a crime scene.
She said the family also needs help with funeral costs, as they now have the unexpected cost of burying two daughters at the same time.
The Oakland Ministerial Alliance will hold a vigil for the victims Sunday night at 6 p.m., at the Oakland Boat Landing.