CEDAR RAPIDS — A Cedar Rapids man was charged in federal court this week for using and interfering with radio transmissions involving railroad operations, including making racial slurs and threats toward Union Pacific Railroad employees.

Randy W. Thompson, 55, was charged Monday in U.S. District Court with interfering with dispatchers or other people while they were involved in railroad operations, a criminal complaint shows.

Authorities started receiving information in March from Union Pacific Railroad that someone was making unauthorized radio transmissions over the railroad’s emergency radio communication lines, as employees attempted to direct trains on proper tracks coming in and out of Cedar Rapids, according to court documents.

Union Pacific Capt. Brian Daniell told a Homeland Security Investigations agent that the suspect was transmitting dial tones and making strange noises over the radio frequencies, court documents show. He was concerned this interference could cause a collision between trains.

In March railroad employees reported the unauthorized transmissions included comments about stealing a train, racial slurs and threats toward railroad employees, court documents show. The railroad reported more than 75 unauthorized transmissions over its frequency in Cedar Rapids were made from December 2016 through March 31 of this year.

Union Pacific Telecom engineers joined the investigation and, using mobile surveillance, tracked down the transmissions originated from Thompson’s apartment building at 919 F Ave. NW. Criminal history checks showed Thompson had a prior arrest in Oklahoma for similar offenses involving a police radio, according to court documents.

During two different searches of Thompson’s apartment, authorities seized radio communications devices and other electronic equipment, according to court documents. During the first search, Thompson claimed to have a medical issue. Officers called emergency personnel and Thompson was taken to the hospital.

At the time of the second search, Thompson, who was wearing a bike helmet, told authorities he was infected with Methicillin-resistant Staphylococcus aureus, also known a MRSA.

A day later, an employee in a marked railroad vehicle parked near the tracks at E Avenue NW, told authorities Thompson approached him wearing a protective helmet and pointed an aluminum bat at him. Thompson told him, “Come and get it if you guys hate me so much. You know who I am, I’m the radio man.”

Railroad officials again reported unauthorized transmissions and one was identified as someone “keying” the microphone of a transmitter for an extended period of time, which prevented railroad officials from using the radio system for normal operations.

Thompson was scheduled to have detention hearing Thursday in U.S. District Court but it was canceled. He remains in the Linn County Jail pending his arraignment.

Thompson also was charged earlier this month in Linn County Associate District Court for violation of fireworks, a simple misdemeanor, a criminal complaint shows.

l Comments: (319) 398-8318; trish.mehaffey@thegazette.com