Sgt. Randy Wilkinson said Garde was being charged with attempted murder and other offenses when deputies were informed by the hospital of the woman's death.
Washington County sheriff's deputies found the Gardes' 10-year-old son asleep inside the trailer, said Deputy Kenny Barnhart, an investigator with the department.
The couple lived in a trailer at 10026 Garis Shop Road, which sits behind a white house occupied by the woman's parents, Mr. and Mrs. Lowell Fox, and the victim's other child, a 16-year-old daughter.
"I was out walking our dog, Gumby, when I heard a loud discussion coming from the trailer,'' said neighbor Jim Cogar. "Then I heard two shotgun blasts outside the trailer.''
A few seconds later, Cogar said a black car sped away from the trailer with its lights out.
Cogar, who lives at 9936 Garis Shop Road with his wife, Carole, said the sounds of arguments coming from the trailer weren't unusual.
Deputy Tom Routzahn was the first officer to arrive and he said he saw Suzanne Garde lying face down near a bush next to the trailer.
As he got closer to the property, Routzahn said he was told to look for a black Pontiac LeMans. But by the time he reached the driveway, it was gone, he said.
"They said it happened by a black car," he said. "When I got here, there was no car."
A car matching that description pulled into the Hagerstown state police barrack a short time later and Garde surrendered, police said.
Routzahn said he thought the shooter was inside the trailer and decided not to get close. He changed his mind when he saw the woman on the ground.
"The dad opened up the window and said, `Oh my God, it's my daughter,'" Routzahn said.
Wilkinson said the victim's mother told deputies she heard her daughter say, "No, Roland! No, Roland'' and then there was the flash of a shot.
Routzahn said he bolted toward Suzanne Garde and dragged her across the stone driveway where a Community Rescue Service rescue worker helped get her into an ambulance.
"The body is going to Baltimore today for an autopsy,'' Wilkinson said this morning.
But he said initials reports were that Suzanne Garde was apparently shot twice, once in the chest and once in the back.
"The weapon was ditched along Garis Shop Road but we recovered it,'' Wilkinson said.
While Routzahn said the shooting appears be a case of domestic violence, he added deputies had not been called to the address recently.
Washington County State's Attorney Ken Long said he was contacted early this morning about the series of events.
"I checked our records and discovered a 1990 charge of battery against Roland Garde brought by Suzanne Garde,'' Long said.
But when the trial date came, the case wasn't prosecuted because Suzanne Garde decided not to testify against her husband, Long said.
A check of Washington County District Court records also turned up a 1989 charge of battery against Roland Garde, which was dismissed.
Routzahn said he has been involved in about 10 dangerous situations over the years, but he said this was the most precarious.
Investigators remained at the trailer hours after Garde turned himself in. Barnhart said investigators were collecting evidence.
He said investigators found a shotgun casing on the ground.