A 23-year-old Wisconsin man who police say threatened to “shoot up” a local school told authorities that classmates humiliated him when he was younger and that he hears voices through his television.

David Etheridge of Appleton, Wisconsin, sent more than 600 electronic messages to the FBI over the past two months, WBAY-TV first learned from police. Among the messages to the FBI was one in which he said he would “shoot up the school,” at which point federal officials notified Appleton Police of the threat on Saturday.

After executing a search warrant on Etheridge’s home, several rifles and “numerous electronic devices” were seized by police. Investigators said that only the “shoot up the school” threat was criminal in nature -- the hundreds of remaining messages he’d sent to the FBI were profane gibberish. Police said they have had repeated contact with Etheridge in the past over domestic violence and property damage incidents.

"Many of them were just repeated vulgarities," says Sgt. Dave Lund, Appleton Police Dept. " Some of them were, the best I can describe, ramblings. Many that just indicated annoyance."

Etheridge described to police that people were trying to hurt him, and the 23-year-old told them stories about how classmates picked on him during his high school years. Etheridge said he’d considered going to the Green Bay Packers organization or local news stations to express his feelings but he held too much fear people were conspiring against him.

Relatives who spoke with Appleton Police said Etheridge was suffering from depression and even referenced purchasing a gun and shooting people in the past. No specific school was mentioned in his shooting threat.

"She said David has previously made verbal statements about how he should just kill himself or get a gun and shoot people up," reads the complaint from his unnamed relative, obtained by WBAY-TV. "However he said when he saw incidents on TV like the recent Florida shooting he would say, 'what's wrong with these people.'"

Despite finding several firearms at Etheridge’s home, local police said such guns were common in the area due to hunting. But just one week from the Stoneman Douglas High School shooting in Parkland, Florida, police Sgt. Dave Lund said they are taking the threat “very seriously.”

Etheridge’s bond was set at $10,000 and he appeared in court Monday to face the charge of making a terrorist threat.