Lydia Sleppy, a teletype operator working for a radio station named KOAT in Albuquerque, claimed she received a telephone call from reporter Johnnie McBoyle on July 7, 1947 at about 4.00pm. McBoyle claimed that the military had recovered a flying saucer in Roswell and that he had seen it, asking Lydia to get ready for a news scoop.
Later while keying in the story being dictated by MacBoyle over the phone on the teletype, she claimed that the machine stopped working suddenly and started sending her a message to "stop communication immediately." She told McBoyle about it and he replied by telling her to forget about it and that she's not suppose to know, warning her to keep quiet about it.
It would appear that the US government not only stopped the news transmission but silenced the reporter McBoyle as well. However a check with the FBI will reveal that that they had no "wire" in that place and that time, hence in no position to tap into and intercept a news transmission. Furthermore, it would reveal that they never bothered opening a file on Lydia Sleppy or eavesdropping on any radio station in Albuquerque.
The teletype machine that Lydia Sleppy used has a manual switch to change between the receive and send modes. Hence, the machine couldn't had stopped working suddenly and receive the threat message unless Lydia had flipped the switch herself! McBoyle refused to talk and hence we can't get any evidence off him.