Two years ago Victor Vassallo, a wealthy Puerto Rican-born industrialist, was killed on a Florida highway while walking for help for his stalled car. He had five sons, including one who, thanks to his father's devotion, had become a world-class swimmer. "I didn't know what to do," Jesse Vassallo recalls now. "It took me a few weeks to think straight because we were a really close family. It was a mess."

Before long Jesse decided that the most fitting memorial to his father would be an Olympic gold medal in Moscow next year. He seems well on his way to achieving that goal. At 17, Vassallo already owns the world record for the 400-meter individual medley and is ranked first in the world in the 200-meter backstroke. At last month's AAU national short course championships in East Los Angeles, he won three events—the 200-yard back and the 200-and 400-yard IMs, setting a new U.S. record in the last event. (Short course championships are held in 25-yard pools. Since some American races are measured in yards and others in meters, records are not comparable.)

Jesse's performance qualified him for the U.S. team that will compete in the Pan American Games in his native Puerto Rico in July. Although Puerto Rico has its own team, its status as an American commonwealth allows Jesse to compete for the U.S. "We all think he should," says his mother, Daisy. "He's been training here for five years."

Born in Ponce, Jesse is one of five swimmers in the family. Marcos, 20, and Victor Jr., 18, are at college on swimming scholarships and Salvador, 10, is already breaking Jesse's age-group records. Vicente, 14, is a competitive swimmer too. Jesse stood out from the age of 6, though, and in 1972 Victor Vassallo, who made his fortune in the plastic pipe business, moved the whole family from Puerto Rico to Florida in search of better training facilities.

Three years later, when he heard about the record-shattering Mission Viejo Nadadores swim club south of L. A. and its coach, Mark Schubert, Vassallo moved his family again. At 14, Jesse barely missed making the 1976 Olympic team. Six weeks after the trials he swam a medley time that would have qualified him.

"He has a fantastic feel for the water, a kinesthetic sense for where the greatest water pressure is," says Mark Schubert. "He's got excellent flexibility in the shoulders, knees and ankles, a lot of physical strength and a tremendous endurance factor. I also think his psychological makeup helps. He's extremely tough. He doesn't let a defeat bother him at all."

Jesse, who is 5'8" and 150 lbs., spends up to seven hours a day working out with both the Mission Viejo high school team and the Nadadores. "He swims at the high school every morning at 5 o'clock," says Daisy, "so I go there with his breakfast before he starts school at 8:15 a.m. When he gets back at night around 7 o'clock, he's usually so tired that he just eats, does a little bit of homework and goes to bed." Jesse manages to watch some television "but I haven't got much personal life—it's mostly swimming."

When he does get out, it's often with Brian Goodell, his closest competitor. Goodell, 20, a Nadadores veteran now at UCLA, won two gold medals in the Montreal Olympics and this March broke Vassallo's 400-yard medley record with a 3:50.80. Jesse came back two weeks later to swim a 3:48.24 to reclaim the record (he also beat Goodell in the 200 backstroke and 200 medley in the same meet). "We work our butts off against each other," says Goodell, "but as soon as we're done swimming, we're the best of friends."

The toughest competition the Americans are likely to face in Moscow is the Soviet team, Vassallo says, and the admiration is mutual. Soviet coach Serge Vaitsehovsky, whose team spent two weeks in Mission Viejo last winter working out with the Nadadores, cautions, "Jesse Vassallo is very, very prepared. He is a very, very dangerous swimmer."