PHOENIX — Kylie McKenzie, once one of America’s most promising junior tennis players, is for now back where she began, hitting balls on a local court, often with her father, living at home while trying to rescue what once seemed like a can’t-miss future.

There is little doubt where that future went astray. In 2018, McKenzie, then 19, was working closely with a top coach at the United States Tennis Association’s national training center in Orlando, Fla.

Anibal Aranda liked to take her to the remote courts of the tennis center, where, she said, he praised her and put his hands on her body during their workouts, pressing against her while she practiced her serve.

Maybe, McKenzie thought, it was because Aranda had grown up in Paraguay and was less aware of the kind of physical contact considered appropriate in the United States. For six years, Aranda had coached for the U.S.T.A., which had been supporting McKenzie’s career and practically raising her at its academies since she was 12. Its officials trusted him, and she trusted them, and so she trusted him, too.

On Nov. 9, 2018, Aranda sat so close to her on a bench after practice that their legs touched, and then he put his hand between her thighs, she said. She later learned she was not the only person to accuse him of sexual misconduct.

During the last week, Aranda has not responded to repeated phone calls and text messages seeking comment, sent to a mobile number associated with his name. Howard Jacobs, the lawyer who represented him during an investigation by the U.S. Center for SafeSport, which investigates reports of abuse in American sports, said Aranda was no longer a client of his.

In his testimony during the SafeSport investigation, Aranda denied ever touching McKenzie inappropriately, either during or after training. He suggested McKenzie had fabricated a story because she had been told that the U.S.T.A. was planning to stop supporting her. Accusing him of abuse, Aranda said, would make it more difficult for the organization to cut her off, an assertion U.S.T.A. coaches and McKenzie rejected.

The SafeSport records are confidential, but The New York Times has reviewed a copy of the final ruling, the investigator’s report, and notes from her interviews with a dozen witnesses, including Aranda. The Times has also reviewed a copy of the police report by an Orlando detective.

“I want to be clear, I never touched her vagina,” Aranda told a SafeSport investigator, according to those records. “I never touched her inappropriately. All these things she’s saying are twisted.”

The incident, which McKenzie quickly reported to friends, relatives, U.S.T.A. officials and law enforcement, led to a cascade of events over the next three years. The U.S.T.A. suspended and then fired Aranda. A lengthy investigation by SafeSport found it “more likely than not” that Aranda had assaulted McKenzie. Police took a statement from McKenzie, stated there was probable cause for a charge of battery, then turned the evidence over to the state attorney’s office, which ultimately opted not to pursue a case. McKenzie said she began to experience panic attacks and depression, which have hampered her attempts to reclaim her tennis prowess.

But what especially troubles McKenzie, now 23, is something that she only learned reading the confidential SafeSport investigative report on her case. An employee at the U.S.T.A had a similar experience with Aranda about five years earlier, but chose to keep the information to herself.

The U.S.T.A. was unaware of that incident because the employee said she did not tell anyone until she was interviewed by the SafeSport investigator for McKenzie’s case.

“To know he had a history, that almost doubled the trauma,” McKenzie said last week at a coffee shop not far from her home. “I trusted them,” she said of the U.S.T.A. “I always saw them as guardians. I thought it was a safe place.”

McKenzie’s case highlights what some in tennis have long viewed as systemic problems with how young players, especially women, become professionals. Players often leave home at a young age for training academies, where they often work closely with male coaches who serve as mentors, surrogate parents and guardians on trips to tournaments.

Chris Widmaier, a spokesman for the U.S.T.A., said any suggestion that its academies are unsafe was inaccurate. He said the organization’s safety measures include employee background checks, training on harassment and how predators target and make potential victims vulnerable to advances, as well as multiple ways to report inappropriate or abusive conduct.

“More than three years ago, an incident was reported by Ms. McKenzie and that report was treated with absolute seriousness and urgency,” Widmaier said in a statement. “The U.S.T.A. immediately, without any hesitation or delay, notified the U.S. Center for SafeSport and cooperated in a full and thorough investigation of the incident. The U.S.T.A. suspended the offending party on the day of the report and has not permitted him back on property or at any U.S.T.A.-sponsored function or event since. In addition to promptly reporting this incident, the U.S.T.A. worked with Ms. McKenzie and her representatives to ensure that she felt safe while she continued to train and advance her tennis career. The U.S.T.A. supported Ms. McKenzie before, during and after the incident.”

Widmaier said the organization was working to increase the number of female coaches. It has added women to its staff at its national training centers — there are now five women, six men and three open positions on its national coaching staff — and developed a coaching fellowship program in which women must account for half the enrollment.

McKenzie has repeated her account of the events on multiple occasions, to friends, U.S.T.A. officials and law enforcement. In finding McKenzie’s account credible, SafeSport investigators wrote that her account had remained consistent and was supported by contemporary evidence, including text messages and U.S.T.A. records.

In 2019, SafeSport suspended Aranda, 38, from coaching for two years and placed him on probation for an additional two years. Aranda is one of 77 people involved with tennis on the U.S.T.A.’s suspended or ineligible list because they have been convicted or accused of sexual or physical abuse.

‘You’re a champion. I want to work with you.’

McKenzie started playing tennis at 4 when her father, Mark, put a racket in her hands. By fourth grade she was being home-schooled so she could practice more.

When she was 12, coaches with the U.S.T.A., who had seen her at tournaments and camps, offered her an opportunity to train full time at its development academy in Carson, Calif. She moved with the family of another elite junior player from Arizona, leaving her parents and two younger siblings behind.

Within a few years she was homesick and burned out. Coaches kept her on the court for hours after training to talk about life and tennis, and one yelled at her while they attended a tournament at Indian Wells when he found out she had kissed a boy at 14.

McKenzie left Carson in 2014 and returned to Arizona. But after she won two top-level junior tournaments, officials with the U.S.T.A. persuaded her to move to the training center in Florida.

A shoulder injury eventually sent her back to Arizona for 18 months, but in 2018 she returned to Florida, moving in with relatives on Merritt Island. She occasionally spent the night at the home of her friend, CiCi Bellis, then a top American prospect. Bellis was injured at the time, allowing her coach, Anibal Aranda, to work with other players.

McKenzie was initially flattered by Aranda’s attention and praise. “He told me: ‘You’re a champion. I want to work with you,’” McKenzie said of Aranda. “I had every reason to trust him.”

One U.S.T.A. employee would have said otherwise.

During the SafeSport investigation into McKenzie’s incident, the employee, who is not being identified to protect her privacy, told the investigator that a few years earlier, Aranda had groped her and rubbed her vagina on a dance floor at a New York club during a night out with colleagues during the U.S. Open. The employee said that she left the club immediately but that Aranda followed her and tried to get in a taxi alone with her, which she resisted.

After the U.S.T.A. employee learned about McKenzie’s accusations, she regretted not reporting her allegations, she told the investigator.

Aranda denied touching the woman inappropriately. He told the investigator he remembered the night at the dance club but did not recall details of the evening.

What follows is the story that McKenzie told U.S.T.A. officials, a SafeSport investigator, police, and shared with The New York Times last week.

By October 2018, McKenzie was training almost exclusively with Aranda, alone with him for several hours every day. Initially, their hitting sessions took place on the busier hardcourts, but he soon moved them to clay courts that got little foot traffic, telling her that the slower surface would improve her footwork. He scheduled training for 11 a.m., though most players practiced earlier to avoid the midday heat.

Each day, she said, Aranda increased his physical contact with her. Pats of encouragement moved down her back until he was grazing the top of her buttocks. He brushed against her as they walked to the courts, making casual contact with her breasts.

He used her phone to film her practice session, then inched closer to her as they sat on a bench watching the video until their legs touched. Sometimes, she said, he held the back of her hand as she held her phone and intertwined his arm with hers. Then he began resting his arm on her thigh as they talked. Sometimes he would say, “You’re too skinny,” and grab her stomach and rub her sides and waist. He would ask her how her shoulder felt and massage it, she told the investigator.

Under the guise of showing McKenzie correct body position and technique, he pushed the front of his body against her back and placed his hands on her hips as she served, moving them to her underwear. Another time, he knelt and held her hips from the front, his face inches from her groin. She dreaded practicing her serve.

He also made her repeat daily affirmations. Some were about tennis, but others were not. “He’d say, ‘Say you’re beautiful because you are,’” McKenzie said.

Aranda told the investigator he used affirmations in training but only those focused on tennis. He acknowledged touching McKenzie’s hands, feet and hips to teach proper body position but denied holding her from behind or touching her groin.

All she wanted was a tennis coach.

On Nov. 9, 2018, McKenzie felt uneasy as she walked to the court for her late-morning training session, certain Aranda wanted to practice serving. He did, she said, grinding against her harder than ever as she practiced her service motion.

At the end of practice he asked her if she thought she was pretty. She was wearing leggings and had placed a towel on her lap. Aranda rested his hand on her right upper thigh. Suddenly, she felt it between her legs, “rubbing her upper labia,” according to the report.

McKenzie elbowed him away. Aranda then knelt in front of her, and started aggressively massaging her calves and knees. He asked her what she wanted him to be. She told him she just wanted him to coach her and provide mental training, an answer that appeared to agitate him.

“Oh, that’s it?” he said, she told the investigator.

As they left the court, she said, Aranda asked her to walk to a shed to store the tennis balls. She walked with him but did not enter the shed. A few minutes later, sitting on another bench, he spoke to her about finding an agent and sponsors. He tried to hug her as she hunched on the bench. She did not hug him back, and left.

McKenzie went to Bellis’s home and, shaking and crying, told her what happened. They called Bellis’s mother, who urged them to report the incident to the U.S.T.A. Bellis and McKenzie called Jessica Battaglia, then the senior manager of player development for the organization. Bellis helped McKenzie, who struggled to speak, retell the story.

Battaglia immediately contacted senior officials with the U.S.T.A., including Malmqvist and Martin Blackman, the general manager of player development, and female employees who needed to be notified, according to her testimony in the report. U.S.T.A. officials informed Aranda that a report had been made and that he would no longer be allowed at the training center.

Ola Malmqvist, then the director of coaching for the U.S.T.A., told the SafeSport investigator that shortly after being suspended, a distraught Aranda called Malmqvist and said: “I’m so sorry. I’m so sorry. I made a mistake.” Then, Malmqvist said, Aranda added, “It wasn’t bad,” and also, “But I made a mistake.” Malmqvist also said Aranda “made some comment along the lines of, ‘I got too close to her.’” Aranda later told investigators that he did not recall making those statements.

Later on the day of the alleged assault, Aranda texted McKenzie to ask whether she had done her fitness workout and also added her on Snapchat. (She supplied the investigator with screen shots of her phone.) When she did not respond to his messages or pick up his phone calls, he started calling Bellis. The friends went to a hotel that night so Aranda would not know where to find McKenzie.

McKenzie gave a sworn statement to the police in Orlando on Nov. 29. The detective wrote in his report that probable cause existed for a charge of battery. But prosecutors wrote to McKenzie in February 2020 to say they did not believe there was enough evidence to prove the case beyond a reasonable doubt.

As the SafeSport investigation unfolded during the first months of 2019, McKenzie continued to train at the center with other coaches. She had persistent stomach ailments and panic attacks, she said, that hampered her breathing when she tried to practice. On many days, she just wanted to sleep. Her love for the game never wavered, though.

She left the center in 2020, when the pandemic forced the U.S.T.A. to cut back. Since then, she has trained with coaches in South Carolina and Arizona. At the moment, she is playing on her own and working out several hours a day at a gym. Sometimes she goes for runs with her mother. She has worked with a therapist and would like to again, but treatment can be expensive, so she is trying to “plow through” on her own, she said.

She completed high school in 2020, at age 21, and is considering attending college, possibly close to home, and maybe reviving her career through N.C.A.A. tennis but while gaining an education, a path several top women have taken, including Danielle Collins, who reached the Australian Open final in January, and Jennifer Brady, who did so in 2021 and used to hit with McKenzie on the U.S.T.A.’s courts. As a junior, McKenzie beat Sofia Kenin, the 2020 Australian Open champion.

She often thinks of the U.S.T.A. employee with her own story about Aranda.

McKenzie, who is soft-spoken and reserved, said she was motivated to speak out because she knows too well what can happen when women don’t.

“That probably just empowered him,” she said of the silence that followed the incident at the New York club. “He felt like he was permitted to act the way he did.”