The crimes happened on December 2, 10 days before Major's murder in the area of Morningside Park.
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The NYPD released surveillance video of two men they believe may be connected.
The first robbery happened around 4:40 p.m. in the dog park.
Authorities say one suspect approached a victim and tried to open a pocket knife.
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The victim punched the suspect and ran for the stairs but fell while running.
Just minutes later, two suspects approached a man who was making a delivery on 118th Street near the park.
The men, wielding a knife and pretending to have a gun, robbed the worker of his cash, cell phone and scooter.
Majors, 18, also ran for the park stairs back on December 11 in an attempt to find help after she was robbed and stabbed.
Investigators are making it clear these robberies are not connected Majors' death, but their proximity to the park is raises concern in a community already on edge.
One of the reasons the victims might be running for the stairs are the guard booths, which are located at 116th Street and 122nd Street, which Columbia says will now be staffed 24 hours a day, seven days a week.
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The NYPD is also adding more officers to patrol the park, and more lighting is planned.
While residents say the surrounding neighborhood has become safer in recent years, there is still concern about the safety in and around the park, especially in the wake of Majors' murder.
Anyone with information on the robberies or the suspects is asked to call the NYPD's Crime Stoppers Hotline at 1-800-577-TIPS (8477) or for Spanish, 1-888-57-PISTA (74782).
You can also submit tips by visiting the CrimeStoppers website at crimestoppers.nypdonline.org or by messaging on Twitter @NYPDTips.
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