Los Angeles Police Department Chief Charlie Beck said Thursday he personally arrested an LAPD officer accused of having unlawful sex with a 15-year-old girl in the department’s embattled cadet program.

Beck said Officer Robert Cain, 31, of the 77th Street Division, was arrested Thursday morning after detectives found evidence that he had sex with a cadet in the division, as they investigated the widening police cadet scandal. Cain was in charge of the process for checking out police equipment “for a certain time period” at the 77th Street Division, according to Beck.

The police chief said he was disturbed by this latest turn of events.

“I find the actions of Cain, if they are proven, to be despicable,” Beck said. “I find them to be absolutely inconsistent with the actions and standards of the Los Angeles Police Department, and they are criminal.”

Seven cadets have been arrested over the past week on suspicion of stealing three police cruisers, a bullet-proof vest, police radios and posing as officers.

Six of the seven were part of the cadet program at the 77th Street Division in South L.A. The seventh was assigned to the Pacific Division in Del Rey.

Beck has suspended the cadet program at the two divisions.

• Related story: Here’s how the LAPD’s cadet youth program scandal unfolded

At this point in the investigation, Beck said, it looks like Cain’s oversight of the equipment at the 77th Street Division was how the arrested cadets were able to get access to police equipment.

Beck added that the department is looking at the officer’s online history to see if there may be other victims.

“There may be a connection to the wooing of this underage female and access to the (police) equipment,” Beck said. “That would be consistent with pedophile-type behavior.”

• Photos: LAPD officer arrested for alleged sex with 15-year-old cadet | LAPD searches Rancho Cucamonga home after arrest of LAPD officer arrested on suspicion of having sex with a minor

Cain has been with the Police Department for 10 years but was never assigned to any of the department’s youth programs, including the cadet program, Beck said. He has no significant discipline history or use-of-force record, Beck added. Police have kept Cain under constant surveillance “since the moment his name surfaced.”

As for the alleged sexual relationship between the girl and Cain, “It appears that it was all consensual, in that there was no force, fear or intimidation used,” Beck said. “But remember, a 15-year-old cannot give consent.”

REACTION TO ARREST

Mayor Eric Garcetti called the charges against Cain “disturbing.”

“There is no higher priority than protecting and guiding our young people — and when they become LAPD cadets, every parent should feel confident that they will be treated with the utmost care every step of the way,” Garcetti said in a statement.

• Related story: LAPD officer accused of sex with 15-year-old cadet oversaw equipment at station

Los Angeles City Councilman Mitch Englander said he will introduce a motion today calling for a “full investigation and audit” of all LAPD youth programs.

The Los Angeles Police Protective League praised the department for arresting Cain.

“If these disgusting allegations are true, we applaud the department for taking swift action to arrest this individual for this vile crime,” the union for sworn Los Angeles police officers said in a statement. “There should be zero tolerance for any officer who takes advantage of those they are entrusted to protect. We are deeply disturbed by this development and condemn this officer’s alleged actions in the strongest possible terms.”

NEIGHBORS SHOCKED

Cain has a home in San Bernardino County.

Shortly after Beck’s news conference, LAPD investigators could be seen swarming Cain’s Rancho Cucamonga home.

• Related story: Is LAPD’s cadet program in jeopardy after 7 cadets were arrested?

Residents in Cain’s quiet, upper-middle class neighborhood said police tape had blocked off the street from about 8 a.m. Thursday.

A group of LAPD detectives was seen in the home’s garage, at one point pulling out a car. By 5 p.m., they seemed to be wrapping up.

“You don’t even know who your neighbors are,” said Alix Sandoval, a 25-year-old mother who lives in the neighborhood.

City News Service and staff writers Doug Saunders and Wes Woods II contributed to this report.