Police are asking the public's help in locating the man who they say killed 16-year-old Appolonia Tucker on Wednesday night in her boyfriend's house on Hoopes Street near 49th, in West Philadelphia.
Police identified the suspect as Gerald Camp, 19.
Homicide investigators believe that an argument led to the death of the young mother.
They said the girl's boyfriend, Jonathan White, 15, and at least one other male were in the house at the time.
Mary Tucker, Appolonia's cousin, said she is relieved that the police have said who they believe killed the high-school sophomore.
"It means a lot, you know, because it means that her baby's father spoke up about who was in the house and what happened when Appolonia got shot," Tucker said.
"It couldn't have been easy though," she added.
The hardest part of all, Tucker said, is knowing that Appolonia's 10-month old baby girl, Jamira, will now have to grow up without a mother.
Appolonia's mother, Yvette, lost her mother, Jannie May, in 1970 after a friend accidently ran over her with his car, the family said.
"There were so many unanswered questions for so long when Yvette was growing up. I just don't want Jamira to have to deal with that," Tucker said.
"It really weighs on my heart."
Camp, who police say has a record of drug arrests, is described as 5-feet-7, 180 pounds, with tattoos on both upper arms - "Deyanna" and a teddy bear.
He has been seen around Delancey Street near 54th and 56th streets and North Fairhill Street.