In late April of 2020, the Porterville Police Department initiated an investigation of elder abuse and credit card fraud. The case was quickly assumed by Detectives after learning there were allegations that the suspect, Joshua Isgrigg, was purchasing illegal firearms and making reference to an apocalypse. Also referenced in the initial reporting were mass shootings, such as the event in Las Vegas, Nevada.

After further in-depth investigation, to include the execution of multiple search warrants, Isgrigg was arrested on June 3, 2020. A search of his vehicle and residence did not uncover the expected illegal firearms, but rather it revealed he possessed the materials required to manufacture a large-scale bomb.

Some of the items seized were large amounts of ammonium nitrate, potassium nitrate, citric acid, along with several others. Possession of these substances are all precursors to the manufacturing of a weapon of mass destruction, similar to those used in the Oklahoma City bombing of 1995. Also uncovered was evidence that Isgrigg was, in fact, using these chemicals to manufacture explosives.

The Porterville Police Department was closely aided in this investigation by Detectives of the Tulare County Regional Bomb Squad and Agents of the Federal Bureau of Investigations.

Isgrigg faced a preliminary hearing on October 1, 2020, where he was held to answer on all charges filed. He is being held without bail in the Tulare County Jail.

Anyone with information related to this investigation is urged to contact Detective Corporal Tyson Tashiro at (559) 782-7400.

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