A convicted felon from Ohio with neo-Nazi sympathies and an illegal arsenal of assault rifles, semi-automatic pistols and other weapons was tracking Jewish and African-American community leaders in Detroit before his recent arrest by a federal anti-terrorism task force, according to a report by Michael Isikoff of NBC News.

“The FBI averted a catastrophe in this case, there’s no doubt about it,” Steven M. Dettelbach, the U.S. Attorney in Cleveland, told NBC News.

The suspect, Richard Schmidt, who spent 13 years in an Ohio prison for killing a man and wounding two others during a traffic dispute, had a notebook in his home with the names, addresses and other personal information of the Detroit area community leaders and their families, the report said. Members of an FBI Joint terrorism Task Force arrested Schmidt, who lives in Bowling Green, Ohio, where he also owns a sporting goods store.

According to the Anti-Defamation League (ADL), Schmidt wasn’t just sympathetic to national socialism; he was a long-time member of the neo-Nazi National Alliance, (NA) acting as the Toledo contact for the group that once dominated the American radical right. Schmidt also occasionally attended meetings of the National Socialist Movement (NSM), currently the country’s largest neo-Nazi group, the ADL said.

“When I saw my name on a piece of paper along with information about our organization and our building written by an alleged neo-Nazi, it was certainly unnerving,” Scott Kaufman, executive director of the Jewish Federation of Metropolitan Detroit, told NBC News.

FBI agents warned the Detroit area community leaders about the possible racist plot after they searched Schmidt’s Ohio home and discovered a video of the 2005 national meeting of the NSM and the notebook. NBC News said the authorities also removed from Schmidt’s home a list of national Jewish-owned businesses and paraphernalia from the Waffen SS.

“It was mind-blowing,” Rev. Wendell Anthony, president of the Detroit NAACP, told NBC about his name appearing in the notebook. “Very unsettling, very disturbing, and it really kind of made me angry.”

Now that a potential bloodbath has been averted, the authorities are trying to determine how Schmidt was able to amass a cache of 18 weapons that included AR-15 assault rifles, 9 mm Ruger and Sig Sauer pistols, shotguns, high capacity magazines and more than 40,000 rounds of ammunition, according to the report. Schmidt was indicted last month, according to the report, on four federal charges, including possession of illegal weapons, body armor and ammunition. He has pleaded not guilty.

Dettelbach, the U.S. Attorney in Ohio, told NBC News that investigators believe the most likely way Schmidt acquired the weapons was at gun shows or through private sales – where under federal law no background checks are required.