A Denville man who kept 109 vials of homemade explosives in a backyard shed pleaded guilty in state court in Morristown on Monday, admitting in front of a judge that the vials held military-style explosive chemicals and accepting a plea deal under which prosecutors will recommend three years in state prison.

Joseph Rizos, 37, a process engineer from Denville in Morris County, New Jersey, pleaded guilty to one second-degree count of recklessly risking widespread injury or damage. Appearing before Superior Court Judge Ralph Amirata on Monday, November 9, he calmly admitted storing 109 vials of homemade explosives, which he said consisted of RDX, PETN, picric acid and TNT, Morristown Green reported from the courtroom.

Source: Morristown Green

What the plea deal says

Morris County Assistant Prosecutor Noelle Fiorentino told the court she will recommend a flat three years in New Jersey State Prison when Rizos is sentenced in January. The second-degree charge he pleaded to can carry up to 10 years, so the recommendation sits at the low end of the range. If Judge Amirata accepts the agreement, Rizos's other state charges — unlawful possession of assault firearms, possession of destructive devices and unlawful possession of large-capacity magazines — would be dismissed.

Fiorentino also said she will ask for the state sentence to run concurrently with any sentence Rizos may receive in his separate federal case, meaning the two sentences would be served at the same time rather than one after the other. Judge Amirata ordered Rizos to remain detained at the Morris County Jail in the meantime. No motive was given by Rizos in court on Monday, and none has been publicly alleged by prosecutors.

How the case began: the June 24 search on Avondale Road

The case began on June 24, 2026, when investigators led by the Morris County Prosecutor's Office searched Rizos's residence on Avondale Road in Denville. Authorities say the search recovered laboratory equipment, instructions for manufacturing explosives, chemicals and containers of suspected explosives, tactical gear and 17 firearms, and that a shed on the property held approximately 109 individual containers of suspected homemade explosive material. Neighbours were evacuated during the search as a precaution.

Source: Morristown Minute / Morris County Prosecutor's Office

At the time of the arrest, Morris County Prosecutor Robert Carroll said the alleged cache was capable of “mass destruction” while matters of national significance were transpiring in northern New Jersey — a remark the local report noted was presumably a reference to soccer's World Cup events in the region. Rizos has been held at the Morris County Jail since his arrest; on July 7, Superior Court Judge Thomas J. Critchley ordered him detained after finding that no conditions of release would adequately protect the public.

A deal he first rejected in August

Monday's plea reverses the position Rizos took three months earlier. At an August 3 hearing in the same Morristown courthouse, he rejected a plea offer built on the same terms — a recommended three years in state prison in exchange for a guilty plea to the widespread-injury charge — and the case was marked for presentation to a grand jury. His defence attorney, Brian Neary, had previously described Rizos as a man with no prior criminal record and a “chemistry savant,” suggested that items prosecutors called blasting caps were thermocouple probes used for monitoring compost in his mother's garden, and claimed the vials contained water and were incapable of detonating. In court on Monday, Rizos admitted the vials were homemade explosives.

The federal case is still pending

The guilty plea settles only the state case. Rizos still faces federal charges filed by the U.S. Attorney's Office for New Jersey: unlawful receipt of explosive materials, unlawful storage of explosive material, and possession of plastic explosives without a detection agent. Federal prosecutors allege he bought fuels, fuses, precursor chemicals and laboratory equipment from online retailers between about April 2020 and June 2026 and stored the materials at his Denville home. He appeared before U.S. Magistrate Judge Leda Dunn Wettre in Newark on August 26 and was ordered detained. The federal investigation involved the FBI's Joint Terrorism Task Force, the DEA and the ATF, among other agencies.

Those federal charges are accusations, and Rizos is presumed innocent of them unless proven guilty. On the federal counts, the receipt and plastic-explosives charges each carry a statutory maximum of 10 years in prison and a $250,000 fine, and the storage count a maximum of one year and a $100,000 fine — maximums are not a prediction of any sentence. Federal prosecutors have not alleged that Rizos selected a target, threatened anyone or planned an attack.