A former Federal Way High School volunteer basketball coach has been charged with third-degree child molestation and communicating with a minor for immoral purposesfor allegedly kissing and fondling a 15-year-old female student.

Brianna Strong, 23, initially denied the sexual relationship, according to charging papers, but she was arrested Friday after admitting to inappropriately touching the girl and exchanging nude photos with her via text message.

Police were alerted to the situation Friday when a Federal Way student informed an officer of an inappropriate relationship between Strong and the student-athlete and began an investigation, according to court documents.

The girl told police that the two met in November when Strong coached her on both her high-school and club basketball teams, according to the charging papers. She said that they began texting and calling each other by pet names like “babe” and “baby,” court documents said.

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The girl also told police that the two discussed their age difference and knew a relationship was illegal, the documents say. She said they talked about waiting to be in a relationship until she turned 16, the charging papers said.

According to the court documents, the relationship became physical when Strong would drive the girl home after basketball practice. The two admitted to kissing on multiple occasions and Strong described two occasions in early 2014 in which kissing turned into sexual contact, according to the charging papers.

The papers also stated that Strong admitted to sending two “nudes” of herself to the 15-year-old and receiving a nude photograph in return, which she claims she never opened and deleted immediately.

Cellphones belonging to Strong and the girl were seized as evidence, court documents said.

Strong is being held in jail in lieu of $70,000 bail. Her arraignment is scheduled for June 23 at the Maleng Regional Justice Center in Kent.

Erin Heffernan: eheffernan@seattletimes.com or (206) 464-3249