Last month, the NYPD urged New Yorkers to help them find a person accused of "creating hazardous conditions" at a Brooklyn subway station, by placing debris on the subway tracks at the Atlantic Avenue-Barclays Center stop. Now investigators have detailed three other times the same person placed other objects, including Christmas lights, a shovel, and other items, on the trackbed at different stations.

As a result of once incident, an R train ran over a fire extinguisher, police say.

"This is a deadly serious matter," NYC Transit President Andy Byford said in a statement. "Anyone who deliberately and recklessly sabotages the City’s main mode of public transportation like this is a menace to New Yorkers and should be caught and prosecuted on the strictest possible terms. We’re working closely with NYPD on their investigation and are determined to help catch whoever is responsible."

The first incident was on May 9th, at the Atlantic Avenue-Barclays Center station, when, according to the NYPD, around 12:31 a.m., a person "placed debris on the northbound rails of the 'D' train line," causing a hazardous condition. No one was injured and no property was damaged during that incident.

Then, on, June 5th, around 2 a.m. at the Union Street subway station, police say the suspect "placed a fire extinguisher, a bank of lights, a bag of concrete mix, and a metal shim on the southbound rails of the 'R' train line causing a southbound 'R' train to run over the fire extinguisher causing mono ammonium phosphate powder to discharge in the station." There was no damage to the train and no injuries were reported. (Mono ammonium phosphate powder is not toxic but can be a "mild irritant.")

Forty minutes later on June 5th, inside the 45th Street subway station, the suspect allegedly "placed a shovel on the southbound rails of the 'R' train line causing a hazardous condition." Again, no injuries or property damage were reported.

On June 9th, around 2:30 a.m. at the 9th Street station, police say the suspect put Christmas lights on the northbound N train tracks, "causing a hazardous condition." No injuries or property damage were reported.

Police release security camera footage of the suspect, who is wanted for reckless endangerment, entering the 9th Street station on June 9th:

He is described as being about 20-30 years old and was last seen wearing a hooded sweatshirt and sunglasses.

Anyone with information in regard to this incident is asked to call the NYPD's Crime Stoppers Hotline at 1-800-577-TIPS (8477) or for Spanish, 1-888-57-PISTA (74782). The public can also submit their tips by logging onto the Crimestoppers website at WWW.NYPDCRIMESTOPPERS.COM, on Twitter @NYPDTips or by texting their tips to 274637 (CRIMES) then enter TIP577.

This post has been updated to include the statement from NYC Transit President Andy Byford.