A New York man was sentenced Tuesday to more than a year in prison for making thousands of harassing telephone calls to members of Congress and threatening to kill a staffer, the U.S. Attorney's Office said.

Ade Salim Lilly, 35, of Queens, New York, was sentenced to 13 months in prison and three years of supervised release, according to the U.S. Attorney's Office for the District of Columbia. Prosecutors accused Lilly of conducting a "campaign of pervasive harassing communications" against members of Congress.

Lilly had pleaded guilty in May to two federal charges: interstate communications with a threat to kidnap or injure, and making repeated threatening telephone calls.

From February 2022 until his arrest in November 2023, Lilly made more than 12,000 telephone calls to about 54 offices for members of Congress across the country, according to court documents. Out of the thousands of calls, over 6,526 calls were to offices within the District of Columbia.

The case is the latest incident involving threats made against public officials, including two Eastern Europeans who were indicted last month for allegedly "swatting" 40 private victims and 61 official victims. Official victims included members of Congress, cabinet-level executive branch officials, senior officials of federal law enforcement agencies, and state officials.

Capitol Police reported in January that threats against lawmakers rose to 8,008 last year from 5,206 in 2018. The Department of Justice also launched a task force in June 2021 to combat threats and violence against election officials, which surged after former President Donald Trump falsely alleged the 2020 election was stolen from him. 

"This is an election year, and more and more often, criticism of a political position or viewpoint crosses the First Amendment line and leads to true threats of violence," prosecutors wrote in a sentencing memorandum. "The pervasive rise in threats against elected officials creates a real risk that expressions of violence will become normalized."

Ade Salim Lilly threatened, harassed dozens of congressional offices

Prosecutors said Lilly placed the telephone calls while he was in Maryland and Puerto Rico. He had moved from Maryland to Puerto Rico during his harassment campaign.

The majority of the calls were answered by congressional staff members or interns, according to court documents. Prosecutors said Lilly would "become angry and use vulgar and harassing language" in some of the telephone calls.

Congressional staff repeatedly asked Lilly to stop calling and Capitol Police also told Lilly on multiple occasions that his calls were "unwanted, and due to a harassing nature, were prohibited by law," according to prosecutors.

Lilly was also accused of making at least one phone call, in which he threatened to kill a staff member at a congressional office in Washington D.C., in October 2022, court documents showed.

During the call, Lilly told the congressional staffer, "I will kill you, I am going to run you over, I will kill you with a bomb or grenade," according to court documents.

In addition to the threatening phone call, prosecutors said that in at least seven cases, Lilly repeatedly called congressional offices that had stopped answering his calls after they became aware he was targeting them. In one instance, Lilly called a congressional representative more than 500 times over two days in February 2023, according to court documents.

His harassment campaign continued until he was indicted and arrested by Capitol Police agents in November 2023 in Puerto Rico.

"Threatening another person’s safety or life is a crime, not protected speech," U.S. Attorney Matthew Graves said in a statement after Lilly's guilty plea in May. "This case should send a clear message that while people are secure in their rights to express themselves, they are not allowed to threaten people and those who do will be held accountable."

Contributing: Bart Jansen, USA TODAY