"I had two pairs of socks and I was still cold," he told the Times.
As they began talking, the officer learned the man's shoe size was 12. He went into a nearby Sketchers shoe store and bought a pair of $100 boots for a little over $75, after the store gave a discount.
The tourist who snapped the photo told the Times that she emailed the NYPD about it later, and that someone responded and asked for the photo so it could be posted.
"I didn't know anybody was around, nonetheless that somebody had taken a picture," DePrimo said.
DePrimo, who never learned the homeless man's name, said he keeps the receipt for the boots in his vest to remind him of some people's circumstances.
"I would love to see him again," DePrimo said.
PBA President Patrick Lynch said in a statement that it isn't unusual for officers to help people in need.
"It happens all of the time and it is usually unseen," he said.
NBC 4 New York has learned that the man in the picture is a veteran who was at one time homeless. Sources say he often panhandles in Times Square and was placed in veteran's housing some time in the past year. It's not clear if he still has a place to live.