On Friday, officials charged Christopher L. Johnson, 27, of Fairfield, Pa., with Grove's murder, after finding him at a nearby camp.
Adams County District Attorney Shawn Wagner said he would consider seeking the death penalty for Johnson.
The killing stunned the small, close-knit group of wildlife conservation officers - "the thin green line" they call themselves - and rippled elsewhere, particularly as hunting season looms.
Gov. Rendell ordered state flags flown at half-staff. "Totally senseless" was how State Police Commissioner Frank E. Pawlowski described the killing.
Pawlowski said Grove's death highlighted how dangerous the unheralded job of a wildlife officer can be - a job increasingly devoted to catching poachers on state and private game lands.
Often, that means patrolling desolate spots during dark hours. In most cases, Pawlowski said, a wildlife officer is "dealing with individuals who are armed."
It was not an unfamiliar scenario for Grove, a boyish-looking officer who had been associated with the Game Commission for nine years. He understood the dangers and routinely wore a bulletproof vest, Pawlowski said.
Grove attended Appalachian Bible College in West Virginia and earned a bachelor's degree in wildlife science from Pennsylvania State University. In 2001, he became a deputy conservation officer, a volunteer post, in Franklin County.
Two years ago, he was one of 21 cadets commissioned full-time officers after a year of training.
Their work includes protecting wildlife and promoting conservation. They have guns, badges, and arrest powers, which they employ increasingly in a state with nearly a million licensed hunters - not to mention those who flout the law.
Pennsylvania bans hunting at night and out of season. The two-week rifle season for deer hunting doesn't begin till later this month.
Still, the state averages about 930 prosecutions for big-game poaching a year, according to the Game Commission. A new law stiffens the penalties for poaching.
Grove had written a story for this month's Pennsylvania Game News, the agency magazine. Titled "A Shot in the Dark," it recounted a night he and a deputy applicant spent chasing a pair of poachers.
"As we drove to our spot for the evening," he wrote, "I explained to him that while we typically put a lot of hours in at night, there is not always action."
Still, he wrote, every year since he had signed on as a deputy in 2001, he had been involved in at least one chase.
Assigned to cover Adams County after graduation, Grove lived in the same town, Fairfield, as Johnson, the man accused of killing him. But authorities said there was nothing to suggest they knew each other.
Johnson had served at least two stints in prison. In 2002, he pleaded guilty to burglary and theft. Three years later, he was jailed again after pleading guilty to child endangerment and other charges.
He and a friend, Ryan Laumann of Fairfield, set out Thursday around 6 p.m. for a night of hunting, Laumann later told police, according to a detective's affidavit filed in the case.
Hours later, they found themselves on Schriver Road, a dark two-lane stretch dotted with cornfields, older farmsteads and newer homes in Freedom Township, just south of Gettysburg National Military Park. The men carried a spotlight and a .22-caliber rifle - to first stun, then kill their prey.
It was only minutes after they'd shot a deer that the game officer pulled up behind their truck, his emergency lights flashing.
Grove radioed for backup and gave the dispatcher the truck license plate number, according to the affidavit. Then he got out of his vehicle and approached the truck.
Sitting in the pickup, Johnson turned to his passenger. He told Laumann that he had a .45-caliber pistol on him and "he wasn't going back to prison," Laumann later told police, the affidavit said. Johnson then got out.
Laumann told police Grove tried to handcuff Johnson and the two men began scuffling. According to the affidavit, Johnson fired at least three times at the officer, then ran to the truck, crying out, "I've been hit!"
Laumann said he and Johnson drove off together but later split up.
Police worked the case through the night. They traced the truck to Johnson - and his relatives led them to Laumann, who promptly agreed to cooperate.
He told them Johnson was headed for a hunters' camp in nearby Franklin Township. Officers found him there Friday morning, and he surrendered peacefully, they said.
Then he started talking.
He told police he had abandoned the pickup and a passing motorist noticed his wound and offered him a ride.
When officers arrested him, they asked Johnson whether he realized he'd shot a police officer.
"No," he replied, according to the affidavit, "I thought it was a game warden."
Johnson was treated at a York hospital and was expected to be held without bail.
Officials did not say whether Grove had a family. They described him as an avid hunter, fisherman, and golfer and a standout officer.
"It's a sad and dark day for the Game Commission," said Robert Criswell, the commission's south-central regional director and a friend of Grove's. "When we take the oath and get our commission, we know this is a possibility. But we've been fortunate since 1915."
Contact staff writer John P. Martin at 610-313-8120 or email@example.com.
Inquirer staff writers Sam Wood and Jeremy Roebuck contributed to this article.