There was a police officer at the door. It was June 2018, in Bradenton, Fla., a Gulf Coast community south of Tampa. The couple who answered the knock quickly realized something was off.

Bradenton Police Sgt. Leonel Marines asked the couple if he could speak to their adult daughter. As Bradenton Police Chief Melanie Bevan told reporters Thursday, Marines had briefly encountered the young woman earlier that day in a parking lot, then followed her home.

Now, at her parents’ door, Marines, 36, said he needed to speak to the daughter regarding a “domestic incident,” Bevan told reporters.

The couple knew their daughter was not involved with any type of situation that required her to speak with police. They refused Marines’s request, then asked for his name and supervisor’s information. When Marines refused to answer and left, the couple immediately called the station to report the incident.

That phone call would eventually tip off police to a pattern of behavior that Bevan said “cast a dark shadow on our law enforcement profession.” According to the chief, her department learned that Marines allegedly had used a sensitive database to mine information for his own personal dating service.

“To get right to the root of the matter, Leonel Marines was not utilizing this data for law enforcement purposes whatsoever,” Bevan said. “Instead, he was using it in a variety of ways — from social media, cold telephone calls, visits to their home under the guise of being there for police business, you name it — trying to get dates with these women. He was very persistent and successful at times in his efforts to do so.”

Marines, a 12-year member of the Bradenton Police Department and a supervisor, was taken off patrol once the initial complaint was made last summer. In October, he resigned. The investigation continued, however, with five detectives eventually reaching 150 women Marines allegedly contacted inappropriately.

“This behavior may have been going on for years, stretching as far back as 2012,” Bevan said.

Bevan said the FBI is reviewing the case for possible criminal charges against Marines. The former police officer has yet to respond publicly to the allegations and could not be reached to comment.

Bevan credited the unidentified parents of the young woman for sparking the inquiry.

“They were heroes, as far as I’m concerned,” she told reporters. “In this day and age, it takes a little bit of courage to tell a police officer standing at their door . . . ‘No, we don’t want to let you talk to our daughter because we don’t get the right feeling about this.’ ”

But the recent episode was not the first time Marines had landed in administrative hot water over his use of a police database. According to the Bradenton Herald, a woman filed a complaint with the department in March 2012 over an encounter with Marines the previous November.

She told the department that Marines had come to her home several times, “asking her personal questions that seemed unrelated to any police investigation and she didn’t know him personally,” the Herald reported, citing an internal affairs report.

Investigators determined that Marines had accessed the woman’s personal information twice using the Driver and Vehicle Information Database, a storehouse of driver and vehicle information that police are supposed to use only for official purposes. The officer told investigators “that there was no particular reason, that they had mutual friends and it was out of curiosity,” according to the report.

Investigators then learned Marines had also accessed the information of eight other people. The officer said he could not remember if he had accessed the data for police business or not. According to the Herald, Marines’ misuse of police data in 2012 resulted in a three-day suspension.

But that administrative slap on the wrist did not apparently dissuade Marines from allegedly continuing to access information about women.

Last June, after Marines’ unsuccessful attempt to talk to the couple’s adult daughter, the family contacted his watch commander about Marines’ concerns about a “domestic” incident.

The watch commander then quizzed his officer about why he had knocked on the family’s door, Bevan told reporters on Thursday. The officer replied that he had followed the woman because one of her headlights was out, and because he suspected she was driving while impaired.

“The two stories really didn’t match up, and when it was brought to my attention, I ordered a further investigation of the incident, which ultimately led to an audit of Marines’ . . . records use, as well as his patrol activity,” Bevan explained. “The results of this audit heightened my concerns even greater due to the discrepancies of the subjects he was conducting queries on.”

According to Bevan, investigators noticed Marines’ searches showed “a very, very clear trend of focusing on female versus male names,” she told reporters. Marines also allegedly focused on Hispanic women who did not speak English.

Investigators contacted around 150 women he had contacted as part of the investigation, Bevan said.

They also determined he had sex with some of the women while on duty. The chief would not go into specifics of how many sexual relationships Marines allegedly had from the information he accessed. She also would not specify what charges the FBI was pursuing as part of the investigation.

But the chief said they do believe there are more women out there who may have had contact with the former officer.

“As far as I’m concerned, he betrayed the oath he swore to,” she told reporters.

More from Morning Mix: