EVERETT — Felony child endangerment charges have been filed against a Lake Stevens couple who allegedly smoked meth while an 11-month-old baby was with them in their vehicle.

The girl’s mother, 22, and her half-brother boyfriend, 35, were charged Thursday with one count each of child endangerment with a controlled substance.

The Herald is not naming the pair to protect the identities of the woman’s children, including two who are of school age. Child Protective Services is involved.

“Investigation is ongoing to determine the extent to which all three children have been exposed to methamphetamine in the past,” deputy prosecutor Andrew Alsdorf said in Snohomish County Superior Court papers.

Marysville police were summoned by a 911 call Dec. 7 about a man and a woman smoking methamphetamine inside a Ford Explorer. The caller was worried that the young girl was being exposed to second-hand smoke from the drug. One of the witnesses asked the caller for help summoning police, in part because he was afraid he was going to punch the man who was smoking meth, court papers said.

A Marysville police officer found the pair in the Explorer, with the woman holding the girl. There were meth pipes in the vehicle. It was 38 degrees that night. The Explorer had no heat because it was out of gas. The girl, dressed only in a diaper, was crying and appeared to be cold and hungry, Alsdorf said.

Both adults allegedly admitted smoking meth that night.

The woman told police she’s addicted to the drug “and readily acknowledged that she is an unfit mother because of her current drug addiction,” court papers said. The man claimed that he’s been smoking meth for 20 years.

“He said it was wrong to endanger the children and there was no excuse for it,” the prosecutor wrote. “He explained that his childhood was a troubled one and that his father introduced him to methamphetamine at approximately 14 years old.”

The pair also told police that they have been in an incestuous relationship for about a half-year, despite having the same mother. The family dynamics are an aspect of the case because the child exposed to meth Dec. 7 is a member of the defendants’ family, adding a domestic violence element to the prosecution.

Both were locked up Friday in the county jail in Everett, their bail set at $150,000. Prosecutors also want court orders prohibiting both from contacting the woman’s three children.

Scott North: 425-339-3431, north@heraldnet.com.