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The video shows the suspect following the victim, Lilian France, into the elevator. As the elevator reaches the fifth floor, the man puts France in a chokehold, as she desperately tries to fight back.

Police say he robbed her before taking off.

Afterwards, France made it to the apartment of her niece, who lives in the building. A neighbor says she described the attack.

"He said to her, 'What floor you coming off?' And she said, 'I'm coming off the fifth floor.' So he said, 'This is your floor,' and she stepped out to come off and he grabbed her back," said neighbor Myrna Branwell.

The attacker made off with France's cane and $900 in cash.

As police continue to search for the attacker, "Operation Impact" is being put to use.

"We have shifted our impact officers to a corridor, roughly in the 70th and 71st Precinct, which is along Flatbush Avenue," said Police Commissioner Ray Kelly. "These case, if you look at them in this pattern, go along roughly a corridor that's either on or parallel to Flatbush Avenue."

Neighbors say they were stunned by the surveillance video of the attack.

"I said, 'Oh my God!' Just so crazy. Holding the lady and choking her," said building resident Carline Simpson.

In New York State, in most cases, it's a felony to attack an elderly victim. That law was passed this year in response to the attacks on 101-year-old Rose Morat and 85-year-old Solonge Elizee. When NY1 spoke to Morat by phone, she said she wants France to stay brave as she recovers.

Meanwhile, the state senator who backed the law says he expects it will prove useful.

"This law today will guarantee that the individual who did this to Mrs. Lilian France will serve a significant amount of time in jail," said New York State Senator Marty Golden.

Until the attacker is caught, neighbors say they will take extra precautions.

"Just make sure you're not being followed and gotta be on your toes," said building resident Raymond Valentin.

"I'm scared of the elevator now. I won't be riding it anymore," said Simpson.

Police also say the suspect, believed to be in his 20s or 30s, could be linked to similar robberies in the area.

A reward of up to $12,000 is being offered for information that leads to an arrest and conviction.

Anyone with information is asked to call Crime Stoppers at 1-800-577-TIPS. You can also send the text message TIP-577 to CRIMES, which is 274637 on your telephone keypad.

Watch the complete surveillance video clip released by police.