Two 16-year-olds have been arrested and charged with the murder of Ahmir Jones, an 18-year-old who was fatally shot in the chest in North Philadelphia last month during a robbery.

Syneef Blackwell and Jameer Martin were arrested last week and charged with murder, multiple counts of robbery, and conspiracy, police announced Wednesday.

Records show Martin lived in the city’s Frankford section and in Johnstown, Pa. Blackwell lived in a foster home.

Deputy Police Commissioner Benjamin Naish said homicide detectives worked with other investigators who were probing a string of armed robberies in the same area and identified Blackwell and Martin as matching the description of those involved in Jones’ killing.

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Blackwell was arrested Nov. 28 and is being held at the county jail on $2 million bail. Martin was arrested Dec. 3 and is being held at the county jail without bail.

Court records show the pair were originally arrested after being identified in a separate armed robbery. Around 12:30 a.m. on Nov. 15, Martin and Blackwell allegedly entered Hok Heng restaurant on the 1700 block of Cecil B. Moore Avenue, where they flashed guns in their waistbands and demanded cash from four people picking up takeout.

Two of the victims handed over small amounts of cash, according to the records, while another was forced to withdraw $60 from an ATM. The young men fled on foot.

The next night, Martin and Blackwell allegedly returned to the same block, where just after 2 a.m., they encountered Jones walking with his girlfriend. One of the young men grabbed the girlfriend’s cell phone, police said, and the other shot Jones in the chest before fleeing. Jones was taken to Temple University Hospital and died less than two hours later.

According to the records, the four victims from the night before were fearful and didn’t immediately alert police. Three filed a report with Temple University Police on Nov. 17, after they saw the news of Jones’ death so close to where they had been robbed.

Detectives initially identified the young men from surveillance videos from the block. In that incident, they were arrested and each charged with aggravated assault, robbery, conspiracy, and related crimes.

Blackwell’s preliminary hearing in that case is scheduled for Dec. 14. Martin’s is on Dec. 16.

Staff writer Anna Orso contributed to this article.