Officials have identified traces of the substance TATP in the explosive device that blew off part of a teenaged tourist's leg in Central Park on July 4th weekend.

TATP, or triacetone triperoxide, is an extremely explosive substance that was used in the Paris attacks in November, as well as by shoe bomber Richard Reid in 2001. The materials that make TATP are commercially available, and officials with the Joint Terrorism Task Force believe "an explosive hobbyist or an experimenter" crafted the explosive and left it in the park, where then-18-year-old college student Connor Golden stepped on it while climbing rocks.

Investigators say it appears someone was testing how to make the explosive, and when it didn't detonate, they left it in a shopping bag in the park. When Golden put his foot on the bag, the pressure triggered the explosion.

Golden, who hails from Virginia and turned 19 this month, had his lower left leg amputated after his foot was blown off. He recently had a second surgery "due to complications from what doctors describe as a local infection in the area of his wound," and is still at Bellevue Hospital. Friends from his hometown started a GoFundMe campaign last week in hopes of helping his family with his medical expenses.

The NYPD is offering a reward of up to $10,000 for information that would lead to the arrest and indictment of the suspected explosive hobbyist.