A music teacher who had already been sentenced to 18 years in state prison for lewd acts against children has pleaded guilty to a federal child pornography charge, officials said Thursday.

John Edward Zeretzke, of Ventura, entered his plea for one count of production of child pornography.

He had previously pleaded guilty in Orange County Superior Court to six state counts of committing lewd of lascivious acts with minors under the age of 14.

Zeretzke taught in schools and other organizations across Southern California while operating Flutes Across the World and was accused of giving semen-tainted flutes to children.

In his most recent plea agreement for the federal case, which dates back to December 2016 to February 2017, Zeretzke admitted to communicating with a girl on the internet and coercing her to produce child pornography, according to the U.S. Attorney’s Office for the Central District of California. The victim did not live in California at the time the crime occurred.

Zeretzke faces a minimum 15 years in prison when he is sentenced in the child porn case on Dec. 3.

Prosecutors will be recommending an 18-year federal prison sentence for Zeretzke that will run concurrent with his state prison sentence, officials said.