CALGARY — A man has been arrested on suspicion of first-degree arson in connection with one of three wildfires that have destroyed more than 700 structures and forced tens of thousands of people to evacuate near Spokane, Washington.The Spokane County Sheriff's Office said Tuesday that Aaron Farinacci, 37, was arrested in connection with the Old Trails Fire, which investigators believe began Sunday afternoon. The fire is one of three major blazes burning in the Spokane area, alongside the Fairview and Meadowview fires.According to AP News, deputies responded after receiving reports of suspicious activity near the area where the Old Trails Fire is believed to have started. Witnesses reported seeing a man in the area shortly before smoke was reported.Farinacci was initially detained and interviewed before being released while detectives continued their investigation. After gathering additional evidence, investigators said they established probable cause to arrest him on suspicion of first-degree arson. He was taken into custody Tuesday and booked into the Spokane County Jail..Farinacci has a previous criminal conviction in Arizona. In 2012, he pleaded guilty to manslaughter and aggravated assault in connection with the 2010 shooting death of his father. He was sentenced to prison and released in 2020, according to court records.The three fires ignited over the weekend and spread rapidly amid hot, dry and windy conditions. Fire officials said the blazes have burned more than 10,000 acres combined and destroyed more than 700 homes, businesses and other structures. Between 64,000 and 67,000 people were placed under evacuation orders as the fires threatened neighbourhoods in and around Spokane. Emergency shelters were opened for displaced residents, while some hospitals and long-term care facilities evacuated patients as a precaution.More than 1,100 firefighters, supported by aircraft, heavy equipment and crews from across Washington and neighbouring states, have been deployed to battle the fires..Washington Gov. Bob Ferguson has declared a state of emergency, and state and federal agencies continue to assist with firefighting and recovery efforts.Spokane County Fire District 3 Chief Cody Rohrbach described the destruction as "an overwhelming amount of damage" as crews continued assessing affected neighbourhoods.The sheriff's office said Farinacci's arrest relates only to the Old Trails Fire. Investigations into the causes of the Fairview and Meadowview fires remain ongoing.Farinacci's bond was set at $1 million, according to court records. He is scheduled to appear in court Tuesday, the allegations against him have not been proven in court.