A New Jersey man who went by “Devilfish” as he sent threatening e-mails to employees at the D.C.-based headquarters of the National Council of La Raza and other Latino civil rights groups was sentenced Monday in federal court in Trenton to 50 months in prison and fined $10,000, federal prosecutors said.

Vincent Johnson, 61, of Brick, N.J., pleaded guilty in October to his years-long campaign in which he sent dozens of e-mails suggesting Latino leaders should have wills prepared, listing them under “RIP” and claiming they were being watched and were “dead meat” who should “get into the American groove...”

The intimidating messages were sent between 2006 and 2009 as he tried to dissuade the groups from advocating for causes important to Latinos including voting, employment rights and access to public schools, Johnson admitted in U.S. District Court for New Jersey.

Johnson pleaded guilty to five counts of interfering with the exercise of civil rights and five counts of transmitting a threatening communication in interstate commerce.

The Internet messages -- which were investigated by the FBI -- went to La Raza; LatinoJustice: Puerto Rican Legal Defense and Education Fund; the Mexican American Legal Defense and Educational Fund; the League of United Latin American Citizens; and the National Coalition of Latino Clergy and Christian Leaders.

Lisa Navarrete, an adviser to La Raza’s president, was among those who received the e-mails in the District. They often surfaced after televised appearances by staff or spokesmen or news accounts of the group’s work, particularly on immigration, she said.

“It ebbed and flowed,” she said in an interview with The Washington Post at the time of Johnson’s plea. She said Devilfish stood out because he “usually was on a long rant” with threats so personal and sustained that they distinguished his e-mails from others that challenge the organization’s activities.