When he graduated in 1998, he joined an elite Navy diving unit that swam with trained dolphins to dismantle underwater mines in Iraqi harbors and elsewhere.
But the 30-year-old Towson native was far from the water when he died. Petty Officer 2nd Class Koth was assigned to a military unit in Baghdad, seeking out and neutralizing roadside bombs. One exploded and killed him Wednesday, according to the Department of Defense.
Engaged and looking forward to having a family, he was about three weeks from completing his second tour of duty in Iraq.
His parents and three siblings said yesterday they take some comfort in knowing that he might have saved the lives of many soldiers and civilians by making a career out of dismantling explosives that inflict so much death and misery.
"Because of me he said that other people would not die," said his sister Christine Koth of Parkville, a scientist at the Johns Hopkins Bloomberg School of Public Health. "He was very proud of that."
His other sister, Jennifer Helfrich, said her brother felt that he could help protect Iraqi civilians by removing bombs that could explode in crowded marketplaces. "He was very sensitive to the horror that the Iraqi people were going through," she said. "He was appalled by the death of his fellow servicemen, but he was also devastated by the loss of Iraqi civilian life."
In his phone calls and e-mails to his family, Petty Officer Koth explained that he was assigned to an Army Rangers unit that would drive around Baghdad in Humvees and Bradley fighting vehicles, looking for roadside bombs and responding to calls from other soldiers.
"They would drive around very, very slowly, and they were fired upon continuously," Ms. Helfrich said. "It was a very dangerous job."
Petty Officer Koth is among the most recent of 2,571 members of the U.S. military who have died since the beginning of the Iraq war in 2003, according to the Department of Defense. About 50 of the dead have come from Maryland.
"I think it's really admirable that a lot of men and women are serving their country in this day and age, despite the unpopular situation that we're in," said Steven Giangrandi, his former diving coach at . "I admire him and his ultimate sacrifice."
Called Austin by friends and family, Petty Officer Koth was born in Towson, the youngest of four children of Gerard Koth, a psychologist who worked for the Baltimore County public schools, and Kathleen Koth, a religion teacher at Calvert Hall College High School.
Military service has been important to the family. Both his grandfathers served in the Navy. On the shelf of his parents' home in Towson is a photo of his four great-uncles, who all served as Navy admirals during World War II.
"He was the epitome of a Navy man," Gerard Koth said of his son. "He never questioned the president, and would never let people know his particular feelings. He just did his job."
Austin Koth graduated from Calvert Hall College High School in 1994. He was a laid-back kid and an avid skateboarder. But he was also intensely athletic, diving on the swim team and playing safety on the football team.
"He was a great guy, a fearless-type guy," said Brian Loeffler, head swimming and diving coach at . "Diving has an element of danger, with the spinning and all that, and he was always trying for more difficult moves."
He joined the Navy after graduating with a degree in information systems. He trained with dolphins at the Naval School of Explosive Ordnance Disposal in Florida.
He served in southern Iraq in 2003, removing underwater mines that posed a threat to ships, and returned this February, his family said. On this tour he was assigned to Baghdad, in the Explosive Ordnance Disposal Mobile Unit Eight, serving with the Multinational Corps Iraq, according to the Defense Department.
Despite 130 degree heat, heavy body armor and constant gunfire, Petty Officer Koth, a triathlete, was determined to keep up his exercise regimen, his family said. He was planning on competing in the Rome Marathon in March. After his dangerous day shifts, hunting for bombs through the streets of Baghdad, he would stay up late at night, running for miles inside Camp Liberty near the Baghdad Airport, his family said.
"He was always very upbeat, and he always minimized the danger when he talked to us," said Christine Koth. "He didn't want us to worry."
The family had not yet completed funeral plans yesterday.