WALNUT CREEK (CBS SF) — A science teacher at middle school in Walnut Creek has been arrested on multiple child sexual assault and child porn charges, according to authorities.

The Contra Costa District Attorney’s Office said 33-year-old Michael Bartel, a science teacher at Walnut Creek Intermediate, was arrested Friday and booked at the Martinez Detention Facility with bail set at $16 million.

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The D.A.’s office said there was no indication that Bartel victimized a student at the school.

The arrest came after an investigation started by the Martinez Police Department when detectives learned Bartel was allegedly talking online about molesting children, the D.A.’s office said.

Bartel was arrested Friday during a traffic stop after a week-long investigation. The same day police and sheriff’s deputies executed a search warrant at both his Walnut Creek Intermediate classroom and his home in Martinez, according to the D.A.’s office.

On Monday, the D.A.’s office said it filed a 16-count criminal complaint against Bartel, including charges of multiple sex offenses against a child under the age of 10, arranging to meet a minor for sex, and possession and distribution of child pornography.

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In a letter to parents, Martinez Unified School District Superintendent C.J. Cammack said that Bartel has taught in both Walnut Creek and Martinez.

“Mr. Bartel was formerly a substitute teacher in the Martinez Unified School District during the 2013-2014 school year,” said Cammack. “For the past three school years, Mr. Bartel has been employed as a teacher in the Walnut Creek School District. Given his past connection as an employee of the Martinez Unified School District, I wanted to make sure our staff and community are aware of this recent development.”

Cammack told parents that there was “no indication that any of the allegations related to Mr. Bartel are in any way connected to his conduct during his work as a substitute teacher for Martinez Unified, nor are there any indications that any allegations involve students he was teaching during his time as a substitute in Martinez Unified.”

Walnut Creek School District Superintendent Marie Morgan sent out a similar letter via email.

Cammack asked parents that if for have any reason they believed they may have information related to this matter please contact the Martinez Police Department at 925-372-3440.

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Bartel was scheduled to make his first court appearance on Tuesday morning.