DES MOINES, Iowa (AP) — A Waterloo man who sent threatening tweets to U.S. Sen. Joni Ernst has been convicted by a jury of sending threatening communications. A federal jury in Cedar Rapids reached the verdict for 34-year-old Joseph Hilton Dierks on Wednesday after five hours of deliberations.

U.S. Attorney Peter Deegan Jr. says evidence showed Dierks sent Ernst several threatening tweets in August, one which suggested he would shoot her and included a link to a 2010 movie in which a man shoots a woman in the head and kills her.

U.S. Capitol Police contacted the Waterloo police and officers to Dierks’ home say he promised to “tone it down.” Within 24 hours he was sending more threatening tweets to Ernst.

He remains in custody and faces up to 15 years in prison.