NEW YORK (CBSNewYork/AP) — A 74-year-old man from Long Island has been charged with threatening to kill two U.S. senators over their support for Brett Kavanaugh’s confirmation to the U.S. Supreme Court, federal prosecutors said.

Ronald DeRisi of Smithtown was charged Friday with threatening federal officials. He was scheduled to appear Friday afternoon at a federal court on Long Island.

According to DeRisi’s attorney, his client is suffering from a form of dementia. Peter Brill told CBS News that the 74-year-old has been diagnosed with “cerebral atrophy” and described his longtime client as “a very sick man.”

Officials declined to name the senators who received the threatening messages.

Prosecutors said DeRisi began leaving the voicemails Sept. 27, the day Kavanaugh appeared before the Senate Judiciary Committee and denied sexually assaulting California psychologist Christine Blasey Ford.

In the first voicemail, DeRisi did not identify himself but claimed to have a “present” for the senator, according to a criminal complaint.

“It’s a 9 mm,” he said, according to the complaint.

U.S. Capitol Police said DeRisi left 10 voicemails for another unnamed senator beginning Oct. 6, the day Kavanaugh was confirmed by the U.S. Senate.

In one of those messages, police said, DeRisi referred to Kavanaugh as a sex offender and warned, “I’m gonna get you,” according to the criminal complaint.

DeRisi made the calls from a pre-paid cellphone that authorities traced to DeRisi’ debit card, prosecutors said.

Investigators used cellphone records and “location information” from a phone provider to determine the calls were placed in the vicinity of DeRisi’s home in Suffolk County, according to the criminal complaint.

DeRisi previously pleaded guilty to making other harassing calls in a case that involved at least 15 calls he placed to a victim’s home and office, according to the complaint.

Earlier this month, Capitol Police charged a former congressional Democratic staffer with entering a Senate office without authorization and publishing the “restricted personal information” of several senators, including their cellphones numbers.

(© Copyright 2018 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)