Philadelphia police expect to file charges soon in the death of a 11/2-year-old girl last weekend, sources said Tuesday.

The toddler, Samari Campbell, was killed by blunt-force trauma on Saturday in the Northeast Philadelphia apartment where she lived with her family. She died after her mother's 20-year-old boyfriend supposedly left her alone in a shower, police said.

Police were called to the girl's home on Blue Grass Road about 6 p.m. The boyfriend, whose name was not released and who is not the girl's father, told officers he had brought the toddler to the shower to clean her up and had left her alone for a few minutes.

When he returned, he said, the toddler was unresponsive and was having trouble breathing.

The girl died about 7 p.m. at Aria Health-Torresdale Campus.

The girl's mother, Victoria Campbell, has two other children, a 3-year-old and a 3-month-old, of whom the boyfriend is the father. She could not be reached for comment.

Initially, Victoria Campbell's boyfriend suggested to police that the older child might have injured the toddler, according to a police source. But that source said the child's injuries were too severe to have been inflicted by another child.

Contact staff writer Allison Steele at 215-854-2641 or asteele@phillynews.com.