WASHINGTON (CNN) -- The North Carolina man who fired an assault rifle inside a Washington, DC, pizzeria while investigating an online conspiracy theory known as "Pizzagate" was sentenced to 48 months in prison Thursday.

Edgar Maddison Welch, 29, also received 36 months of probation and was ordered to pay $5,744.33 in restitution for firing multiple shots with an AR-15 rifle inside the Comet Ping Pong restaurant in northwest Washington in December. He claimed he was attempting to find and rescue child sex slaves that he believed were being held at the restaurant -- a belief allegedly based on his reading of a false story circulating online at the time.

After Welch found no evidence of child sex-trafficking at the restaurant, he did not harm anyone and surrendered.

He pleaded guilty to gun charges in federal court in March.