WALTHAM — Former Olympic swimming coach Joseph Bernal dropped out of sight last fall.

One day, neighbors saw Bernal, then 74, sitting in his car in the driveway of his Dutch Colonial on Ellison Park. As usual, he left the engine running while he talked on the phone. The next day, prospective homebuyers appeared at his doorstep. And, as one neighbor said, it was as if Bernal “disappeared overnight.’’

The January sale struck many on Ellison Park as extraordinarily strange. Bernal had lived in the neighborhood for almost two decades and poured money into his home over the last few years, installing solar panels and an elaborate backyard deck. He didn’t strike neighbors as a man preparing to leave town in a hurry.

But Bernal had good reason to do just that.

On Feb. 23, USA Swimming banned the seven-time Ivy League coach of the year for life because he violated sexual misconduct policies designed to protect athletes. It’s unclear whom Bernal targeted or how many victims exist. But two sources familiar with the situation confirmed that a complaint from a female swimmer initiated an investigation by USA Swimming.

The lifetime ban marked the end of the investigation, which started shortly before Bernal listed his home for sale in November 2015, and the end of a coaching career that spanned nearly 50 years. And it left some in the close-knit US swimming community surprised.

“The allegations that USA Swimming adjudicated and found credible are not characteristic of what I saw as an athlete in his program,’’ said David Berkoff, a former world record-holder in the 100-meter backstroke and four-time Olympic medalist. “I was surprised. It’s not something I saw when I was on the team. It was very difficult for me to hear of this ban.’’

Berkoff swam for Bernal in the late 1980s and early ’90s, including four years at Harvard, and competed in the 1988 and 1992 Summer Olympics.

Prior to his lifetime ban, Bernal was a respected coach who boasted a résumé with five Olympians, including two world record-holders and 51 Olympic trials qualifiers. He was a member of the Olympic coaching staff for the 1984 and 1988 Games. While coaching at Harvard from 1977-91, his teams won seven Ivy League titles.

Most recently, he was the head coach and owner of Bernal’s Gator Swim Club in Waltham. For decades, the club’s swimmers successfully competed nationally in a range of age groups and at top colleges.

Last fall, Bernal was inducted into the American Swimming Coaches Association Hall of Fame and remains listed on its roster of inductees. Asked whether Bernal would be removed from the Hall of Fame, ASCA executive director John Leonard said in an e-mail that “a new policy is under consideration,’’ but he declined to comment on what may happen with a specific case until lawyers review the proposed policy.

According to USA Swimming, the policies Bernal violated include “any sexual contact or advance or any other inappropriate sexually oriented behavior towards an athlete’’ by someone in a position of authority and “any nonconsensual physical sexual conduct, or pattern of unwelcome advances or other sexual harassment’’ in connection to USA Swimming-related activities. The policies cited in the Bernal ban announcement also included sexual misconduct “directed toward any member or other person participating in the affairs or activities of USA Swimming.’’

While USA Swimming representatives wouldn’t provide any details about the Bernal investigation, organization spokesman Scott Leightman said in a statement, “USA Swimming is deeply committed to the safety and welfare of all its members. The Safe Sport program’s mission is to increase awareness to reduce the risk for abuse in sport and our organization has no tolerance for violations of our code of conduct.’’

Once a complaint comes into USA Swimming’s Safe Sport staff, the organization gathers information and refers the issue to law enforcement “as appropriate.’’ If USA Swimming determines there is the possibility of a code of conduct violation, then the matter is reported to outside legal counsel and a formal investigation is started by an outside investigator. If the investigation uncovers evidence of misconduct, then a hearing before the National Board of Review typically takes place. After the hearing, USA Swimming determines what action it will take, including whether to enact a lifetime ban.

Not first to be sanctioned

Since 1991, USA Swimming has banned 136 members for life for violation of its code of conduct, including 92 men — six with ties to Massachusetts — for sexual misconduct.

One of the most recent lifetime bans was issued on April 28 to Andrew Picard, an 18-year-old who attended Eton, the prestigious British boarding school. Picard, whose parents own a house on Nantucket, registered with USA Swimming and competed in a few stateside swim meets. He was caught with more than 2,000 indecent images of children on his computer in his school dormitory and, in a controversial, headline-making judgment, given a suspended prison sentence.

Members who are banned or suspended can appeal the decision to the USA Swimming board of directors. According to sources familiar with Bernal’s case, the Waltham-based coach initially appealed USA Swimming’s decision and the appeal was denied.

“As a former USA Swimming board member, I have sat on several appellate decisions of the board of review,’’ said Berkoff, who was not involved in the adjudication of the Bernal case. “I have confidence that the process is just. And I have confidence more often than not that the decision is correct.’’

When the Middlesex County District Attorney’s Office was contacted about Bernal and asked whether there were any ongoing investigations into the matter, spokeswoman Liz Vlock said that the office “does not confirm or deny whether there are pending investigations.’’

Multiple sources who knew Bernal before the ban said they have heard that he moved out of the country.

Keeping a low profile in the United States or elsewhere would be a change from how Bernal lived previously. Berkoff described Bernal as “a bit of a showman when it came to being a coach.’’

Neighbors recalled Bernal as someone who cared about appearances, dressing well, driving BMWs, and meticulously tending to his yard and home.

“When I was a 10-year-old kid, I saw a picture of Joe surrounded by the Harvard swimmers from 1979 and he’s wearing a three-piece suit surrounded by these big, strapping guys hoisting a trophy,’’ Berkoff said. “I thought, ‘Wow, I’ve never seen a swim coach wear a three-piece suit to a swim meet before. I’d like to be part of that team someday because they look classy. They look professional.’

“He helped instill a quality work ethic and the ability to dream into me,’’ Berkoff added of Bernal. “That’s the kind of person I knew. Obviously, there are other people who didn’t have a good relationship and experience with him and it’s unfortunate.’’

Appearances were deceiving

Neighbors on Ellison Park described Bernal as “nice enough’’ and they appreciated how tidy he kept his yard. Sometimes they would see Bernal outside with younger women, but not women who appeared underage.

At one point, his mother lived at the home on Ellison Park. During another stretch, his son, Craig, lived there. Bernal also has a daughter, Michelle. She coached for Bernal’s Gator Swim Club. She worked as executive director and associate head coach at the club from April 2010 until October 2015.

Berkoff, who is now a lawyer in Missoula, Mont., and coaches the aquatic club there, remembered Michelle riding to swim meets with her father on the Harvard bus when she was 9 or 10 years old. He said that Craig would sometimes also ride on the team bus. Berkoff has not seen or spoken to Bernal since the American Swimming Coaches Association clinic in September 2015 in Cleveland.

Fordham University, where Bernal coached from 1966-78, removed him from its 2009 Hall of Fame class in early May.

In a statement, the school said, “Though there have been no criminal complaints against him, much less convictions, to leave in place Mr. Bernal’s honors would send the wrong message to our current and former student-athletes.’’

Bernal’s Gator Swim Club has a new name and new ownership. The Gator Swim Club was formed on Jan. 27, when the assets of the club Bernal founded were purchased two days before the sale of his Ellison Park home.

In a statement, new team owner Anne Frazier made it clear that the Gator Swim Club has “no relationship to Joe Bernal,’’ and that he is not employed by or involved in any club operations.

“I have always felt that coaches are in a position of incredible trust and caring for their athletes,’’ said Berkoff, whose campaign for a spot on the USA Swimming board of directors emphasized protecting athletes from abuse. “I’ve seen, heard of . . . coaches who cross that line and take advantage of their role as a mentor. Whether that line crossing is because the coach is a pedophile or because they forget that they are in a position of trust and they’re not a peer, it doesn’t matter to me. What matters is that athletes are protected from coaches who cross that line. I’ve always felt that way.’’

“But it’s really hard for me to put into words how I feel [about Bernal]. On one side, I believe very strongly that USA Swimming needs to hold any member or former member who has committed an act in violation of our code of conduct accountable. And I think we’re doing a good job as an organization in pursuing that as a policy. At the same time, Joe was my coach and it’s hard for me to believe and accept that this is what has happened.’’

Shira Springer can be reached at springer@globe.com.