An arrest warrant was issued for Justin Smith, 23, last month. He is charged with the murder of 21-year-old Dianna Brice and her unborn child.
Brice was reported missing by her mother in Upper Darby, Pa. on March 30. Brice's body was found in the 5800 block of Eastwick Avenue in Southwest Philadelphia on April 5.
She had been shot multiple times in the head.
During a briefing on domestic violence Wednesday, police said Smith is still considered to be armed and dangerous.
"This individual has been on the run for some time so we can really use your help," said Lt. Frank Vanore of the Philadelphia Police Department.
Vanore added that, as with all Philadelphia homicides, there is a $20,000 reward for information leading to Smith's arrest and conviction.
According to the FBI, Smith has connections to New Castle, Delaware; Greensboro, North Carolina; the Little Haiti neighborhood of Miami, Florida; and Atlanta, Georgia.
Brice and Smith were last seen at K Laundry in Yeadon on March 30.
Investigators believe Smith fatally shot Brice inside his car. That car was found engulfed in flames in the area of 59th and Florence streets in Philadelphia.
No one was found inside the vehicle. The car was discovered about a mile from where police said Brice's body was discovered in the woods days later.
WATCH: Philadelphia DA's Office provides update on Dianna Brice murder case
Police previously announced the arrest of 21-year-old Tylydia Garnett in connection with Brice's death. She was charged with arson, abuse of a corpse and related offenses.
Investigators said Garnett was seen on video buying gasoline before returning to a garage that was either rented or owned by Smith.
They loaded something into Garnett's car, which is believed to be Brice's body.
Investigators said Garnett then followed Smith to the location on Eastwick Avenue where Brice's body was found.
The Philadelphia District Attorney's Office said Garnett fled to Florida after helping to dispose of Brice's body. She was released after posting 10% of $75,000 bail.
Brice's mother, Betty Cellini, said her daughter had a young son and was 14 weeks pregnant. She also had a life-threatening medical condition that required medication.