Investigators say that the younger of two suspects charged after hazardous and explosive materials were found at a residence in Richmond Hill last week was “on the cusp of radicalization,” a source close to the investigation tells CTV News Toronto.

On May 9, York Regional Police received information from the U.S. Customs and Border Protection and the Canada Border Services Agency about a suspect they were investigating who lives in their region.

One day later, officers executed a search warrant at a home on Larratt Lane, near Shaftsbury Avenue and Bathurst Street, where they allegedly found “hazardous, explosive materials” and a detonator.

Residents of nearby homes were evacuated as a precaution while officers removed the items.

CTV News Toronto has learned that officers found the chemicals, which included mercury, red phosphorous and ammonium-nitrate, in the Richmond Hill home’s garage and an adjacent shed.

Police also found a copy of “The Anarchist Cookbook,” a book with instructions on how to make explosive devices as well as manufacture drugs and modify electric devices.

“Every person who has blown anything up has gone to that book,” the source said.

On May 13, police arrested two men in connection with the case.

The suspects, identified as Mahyar Mohammadiasl, 18, and Reza Mohammadiasl, 47, who are father and son, have each been charged with one count of possession of an explosive device.

The source also told CTV News Toronto that investigators came across “a sea of red flags for being on the cusp of radicalization” concerning the 18-year-old suspect.

Mahyar Mohammadiasl’s cell phone is in the possession of the U.S. FBI and investigators are examining his other electronic devices, the source said.

When asked about the incident earlier this week, Public Safety Minister Ralph Goodale told CTV News Toronto that the investigation posed no threat to national security and was a local police matter.

A judge granted a $50,000 on behalf of them both on Friday. As part of the conditions, Mahyar Mohammadiasl must be with one of sureties at all times.

They are due back in court on June 6.

The charges have not been tested in court.