NEW YORK (CBSNewYork) — The NYPD on Friday renewed its call for help solving a five-year-old cold case.

A young man lost part of his leg in an explosion in a corner of Central Park in July 2016. His father spoke with CBS2’s Dave Carlin about the mystery.

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“We just don’t see there being a significant progress,” said Kevin Golden.

July 3, 2021 marks five years since Golden’s son Connor lost his lower leg when he stepped on an explosive booby trap left in Central Park by a bomber who’s not been caught.

Connor has since learned how to walk and run with his prosthetic, and he graduated university.

He was 18 when he visited an area of the park near Fifth Avenue and East 60th Street with friends. He jumped off a rock and onto a bag full of explosives.

Police determined the bag was from La Unica Bakery in Union City, New Jersey.

“I’m surprised that that didn’t conjure up more interest or leads for the police,” Golden said.

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The NYPD renewed the call for help this week, reminding the public of the $40,000 reward for information.

Members of the Golden family said they were disappointed in Mayor Bill de Blasio’s initial comments about the case and recent ones he made about firework safety.

“Mayor de Blasio made some statements… ‘Oh, let fireworks be done by the professionals.’ That’s what he chalked up this incident to five years ago. ‘Oh, fireworks mishap.’ It’s totally bogus,” Golden said.

Family members said Connor won’t comment publicly at this time.

“His mindset is look forward, not backwards,” his father said. “We’re so proud of him, how he got through it.”

Connor is a musician and marketing his invention called “Skym,” an app that turns smartphones into musical instrument digital interface devices.

Meantime, his family is keeping pressure on police to get justice and closure.

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The mayor’s office has not responded to CBS2’s request for comment.

Dave Carlin