BAY CITY, Mich., (AP) — A 76-year-old northern Michigan man pleaded guilty Monday to leaving two pipe bombs outside cellphone stores n Cheboygan and Sault Ste. Marie, federal prosecutors announced.

John Douglas Allen of Whittemore entered the plea in federal court in Bay City. He faces up to 20 years in prison when he is sentenced, which is scheduled for Nov. 9.

Allen admitted that on Sept. 15, 2021, he placed pipe bombs containing shrapnel outside an AT&T store in Sault Ste. Marie and outside a Verizon store in Cheboygan, prosecutors said. Both pipe bombs contained a note demanding $5 million. Video footage taken from the stores and nearby businesses captured his actions.

Allen also pleaded guilty to placing letters containing threats aimed at telecommunications providers at cell towers ion the Upper Peninsula.