TROY, Mo. - A Lincoln County sheriff's deputy acted recklessly when he fired shots through a pickup's rear window and killed two men last fall, authorities said Thursday after filing felony charges against the officer.

Nicholas Forler, 26, of Troy, is charged with two counts of involuntary manslaughter. Accompanied by his lawyer, Joe McCulloch, Forler surrendered to authorities and was released after posting $30,000 bail. Involuntary manslaughter carries a maximum sentence of seven years in prison.

After a brief chase that ended in a driveway, Forler shot Tyler Teasley, 22, of Silex, and Michael Brown, 23, of Troy, on the night of Oct. 23 as they sat in Teasley's extended-cab pickup. Both men died of head wounds.

Teasley's father, Brent Teasley, said Forler should have been charged with a more serious crime.

"Obviously, whenever you shoot somebody in the back of the head, it's first-degree murder," Teasley said.

Lincoln County Sheriff Dan Torres, who dismissed Forler after the charges were filed, said that before the shooting, the deputy had been "a very good employee." Forler had been a deputy for three years.

"He was an extraordinarily good detective," Torres said, adding that Forler had been promoted to supervisor of a road patrol.

Missouri Highway Patrol Sgt. J. Sam Steward said in a court document that the shooting happened after Forler tried to stop Teasley's truck for speeding. The Highway Patrol investigated the shooting. After the chase, the truck stopped in a driveway just off Highway 47, a short distance west of Troy. Forler got out of his patrol car, which he had stopped behind the pickup, and stood between the vehicles.

Steward gave this account:

As the truck began to roll slowly backward, Forler shouted for it to stop, then "recklessly fired" a shot from his .40-caliber Glock pistol at the driver's side of the truck's tinted rear window. He shouted a second time, then fired again. Forler then moved out of the way of the truck, which rolled into the front of the deputy's patrol car.

Brown had been seated behind Teasley, the driver. The deaths outraged the men's family and friends, who have demonstrated regularly outside the sheriff's office.

Torres said Thursday that authorities owed the families and Forler a "complete and thorough investigation in order to determine all the facts." The sheriff declined to discuss the shooting in detail because of what he said were pending civil suits filed by the families against his department.

Brown's mother, Donna Brown, said she preferred more serious charges against Forler but was satisfied with involuntary manslaughter.

Misty Brown, 22, a cousin who had identified Brown's body for authorities, said: "I'd like the cop to know that's the last image in my head of my cousin and it's his fault. I'd like to eventually sit down and talk to him face to face - see if he has any remorse."

Janice Spires, an aunt of Brown's, said her family is "terribly disappointed" and "shocked" with the decision to charge Forler with manslaughter instead of a more serious crime.

"Our family has been in agony for months, and we feel this is a slap in the face," Spires added.

Teasley and Brown had been among six people - three men and three women - in the truck. Two of the women have said the deputy fired into the truck without warning. They added that the truck rolled backward because Teasley had left the vehicle out of gear.

One of the women said the six friends were "freaking out" over being pulled over because they had alcohol in the car. They were celebrating the 18th birthday of the third woman in the vehicle.

Attorney General Jay Nixon's office filed the charges in Lincoln County Circuit Court. Nixon's office took over the case after the county prosecutor, John Richards, recused himself from the matter.