A former Glendale police officer accused of sending sexually explicit text messages to teenage girls and sexually abusing one of them will not be prosecuted.

The Maricopa County Attorney's Office decided not to pursue a case against 25-year-old Christopher Balmaceda, who had worked off-duty at Mountain Ridge High School, despite a recommendation from police that he be charged with one count of sexual abuse and four counts of luring a minor for sexual exploitation.

"We determined there was no reasonable likelihood of conviction in this case," said Jerry Cobb, a spokesman for the County Attorney's Office.

He said prosecutors were concerned about the 17-year-old girl who said she was sexually abused. The teen said she aimed to report the officer's wrongdoing.

The teen told Glendale detectives that "her plan was to get enough information to tell someone what Christopher was doing," according to the police report.

Those statements made it difficult for prosecutors to prove a lack of consent to sexual abuse and explicit text messages, Cobb said.

The spokesman said prosecutors also believed they didn't have the evidence to charge the former officer with luring, as a cellphone provider couldn't provide the text of messages, only the number of messages between Balmaceda and students.

Sgt. Brent Coombs, a Glendale police spokesman, said detectives communicated with prosecutors early in the investigation and submitted what they believed to be a "very thorough investigation."

Glendale police launched an internal probe of Balmaceda in late January after a report that teens had received suggestive messages from Balmaceda.

Police found that Balmaceda, who worked at the school twice a month, had sent about 3,600 text messages to female students from September 2010 through January, according to an internal investigation.

Police began a criminal investigation after a 17-year-old said Balmaceda, a married father, had kissed and touched her in January after she met him at an abandoned grocery store while he was on duty.

Investigators confronted the officer.

"Balmaceda admitted to me that from September 2010 through January 2011 he sent numerous sexually explicit text messages to four female Mountain Ridge High School students for the purpose of gratifying a sexual desire," a Glendale sergeant wrote in an internal review.

According to the report, Balmaceda also admitted to the encounter with the 17-year-old. He submitted a resignation letter two days after the interview.

He did not speak to detectives investigating potential criminal violations. Federal law prevents prosecutors from discussing confessions or admissions during internal police investigations in court.

Balmaceda would not comment on the allegations or the latest decision.

Two former sex-crimes prosecutors raised questions about Maricopa County attorneys' decision not to charge the former officer.

The presence of multiple victims and Balmaceda's status as a police officer made this an important case to pursue, said Robin Sax, who spent 15 years as a sex-crimes prosecutor in Los Angeles.

"The touching plus the texts is way beyond what you would need for some charge," Sax said. "We hold people who take care of our children to a higher level."

Robert J. Campos, a Phoenix defense attorney who spent five years in Maricopa County's sex-crimes unit, said he was concerned by the officer's communications with at least four students.

Still, he acknowledged that prosecutors may have hesitated if the victim didn't seem credible.

"When you talk to somebody who's been a victim, you're either going to immediately believe them or you're going to be unsure," Campos said. "If at a gut level, I believed, I took it to trial and I always won those cases."