A Marin County man whose abandoned truck led police to evacuate a sleepy Rohnert Park street was in custody Wednesday on suspicion of leaving potentially explosive materials in the vehicle.

Mark VanMidde, 49, of Woodacre was booked into Sonoma County Jail on $50,000 bail on an arrest warrant stemming from the July 31 evacuation, authorities said.

VanMidde's dusty blue Chevrolet flatbed truck had been gathering cobwebs for perhaps months in front of his estranged wife's home on Mary Place, police said.

When his son prepared to move it on July 31, VanMidde apparently warned him in text messages that "there might be explosives in it," Rohnert Park Lt. Jeff Taylor said.

At the time, police contacted VanMidde by phone. Although he initially denied the presence of explosives, he eventually told police "there was a grenade simulator, and it would explode if a person picked it up," Taylor said.

Officers and fire personnel evacuated about 20 homes on Mary Place near Bodway Parkway. The UC Berkeley police bomb squad, contracted by Rohnert Park, removed several chemicals and a flash-grenade simulator from the truck's locker, Taylor said.

The university bomb unit determined that the materials included a partial bag of ammonia sulfate and a full bag of ammonia nitrate. The chemical compounds are commonly used as fertilizers, but when mixed they can explode.

The bomb squad also determined that a pink liquid in a gallon container was nitromethane, a compound sometimes used to stabilize chlorinated solvents.

The grenade was a "simulator projectile ground burst," a device designed to mimic battle sounds and effects, according to military websites.

VanMidde, who was separated from his wife at the time, refused to tell police where he lived or help them further, Taylor said.

He told police that he had the materials because he worked in construction, Taylor said.

About one month after the evacuation, Rohnert Park police received the UC Berkeley team's report and forwarded the investigation to the Sonoma County District Attorney's Office recommending an arrest.

A judge issued an arrest warrant for VanMidde on Jan. 15 on suspicion of possessing illegal explosives and recklessly or maliciously having explosives on a public street, according to the Sonoma County Sheriff's Office warrant database.

On Monday, Marin County sheriff's deputies arrested VanMidde, who was living in Woodacre, according to Marin County Jail booking records. He was moved to the Sonoma County Jail on Wednesday and was scheduled to appear in court at 1:30 p.m. Friday in Department 9.

You can reach Staff Writer Julie Johnson at 521-5220, julie.johnson@pressdemocrat.com or on Twitter @jjpressdem.