Updated

The New York Police Department is questioning a man they have dubbed "John Doe Duffel Bag" as a person of interest in the serial killings of three Brooklyn shopkeepers, and say they have recovered the weapon they believed was used in all three murders.

MyFoxNY.com reports the man, who authorities nicknamed after seeing him on surveillance footage carrying a duffel bag, came in voluntarily for questioning and is not considered a suspect at this point.

An official tells the Associated Press a sawed-off Ruger rifle that had a makeshift light on its barrel was found Wednesday in the man's duffel bag. The official was not authorized to speak publicly and spoke to the AP on condition of anonymity.

The official says the bag also contained the .22-caliber ammunition found at the scene of all three shootings this year, black gloves and women's stockings.

The man was caught on film near the scene of the Friday murder of 78-year-old Rahmatollah Vahidipour, who was shot three times as he was closing up his shop just after 7 p.m.

The New York Post reports authorities later matched casings left at the scene to two other killings of two shopkeepers on July 6 and Aug. 2, suggesting all three murders were committed with the same .22-caliber handgun.

In July, 65-year-old Mohamed Gebeli was shot to death in his clothing store and 59-year-old Isaac Kadare was stabbed in the neck and shot in the head roughly one month later at his 99 cent store.

All three of the victims were of Middle Eastern descent and in each case the victim's face and head was covered with clothing, but very little money was taken. The victims' shops were within a four mile radius of each other, and all three men were apparently closing for the night when they were murdered.

The Post reports a man who resembled "Duffel Bag" was captured on security film near the scene of Kadare's murder, but NY Police Commissioner Ray Kelly later dismissed the similarity.

The NYPD has offered rewards of $22,000 in each of the homicides for information leading to the arrests and convictions of the person or persons responsible. 

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The Associated Press contributed to this report.