By Cherri Gregg

PHILADELPHIA (CBS) – Philadelphia police have made an arrest in the murder of a South Philadelphia woman whose body was found early Thursday morning in the basement of her home.

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Authorities say the murder took place inside a home along the 2300 block of South Mildred Street. The 24-year-old victim, identified by police as Tiffany Gillespie , was pregnant.

Police arrested 19-year-old Aaron Fitzpatrick at about noon. They say he shot and killed his pregnant girlfriend during a domestic dispute.

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Gillespie was found by her mother, lying in her basement with a gunshot wound to the head. Police say the victim and Fitzpatrick were no strangers to police and they had a very tumultuous relationship.

“They had been arguing over the last 24-hour period. He was upset with the fact that she was pregnant with his baby and he killed her for that,” said Homicide Captain James Clark.

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Police say they are waiting for a results from the medical examiner to determine how far along the victim was in her pregnancy when she was killed. At this point, police say Fitzpatrick will be charged with only one count of murder.