The Washington Post: FBI acknowledges it tested NSO Group’s spyware.
https://www.washingtonpost.com/technology/2022/02/02/pegasus-fbi-nso-test/

"The FBI tested Pegasus spyware made by the Israeli company NSO Group for possible use in criminal investigations, even as the FBI and Justice Department were investigating whether the NSO software had been used to illegally hack phones in the United States, people familiar with the events have told The Washington Post.
"Justice Department lawyers at the time discussed that if the FBI were actually to deploy the tool, it could complicate any subsequent prosecution if the department brought charges, according to the people, who spoke on the condition of anonymity because of the matter’s sensitivity."
"In a statement to The Post, the FBI confirmed that it had tested the spyware but stressed it had not been used “in support of any investigation.” "