( CNN ) -- Sherry Johnston , whose son is having a baby with the daughter of Alaska Gov . Sarah Palin , was arrested Thursday on drug charges , Alaska State Police said . Bristol Palin , the eldest daughter of Alaska Gov . Sarah Palin , and her boyfriend , Levi Johnston , in September . Johnston 's teenage son , Levi , is the boyfriend of Bristol Palin , eldest daughter of the former GOP vice-presidential nominee . Johnston was arrested in her home in Wasilla , Alaska , on six felony counts of misconduct involving a controlled substance , police said . The warrant resulted from an undercover investigation that `` had been going on for a while , '' Alaska State Trooper spokeswoman Megan Peters said . Peters would not describe the type or amount of drugs allegedly involved in the arrest , saying such disclosures `` could hamper the investigation . '' Deborah Miller , supervisor of the criminal department in the clerk 's office in Palmer , Alaska , told CNN that Sherry Johnston was released on bail and is scheduled to be arraigned January 6 . Palin spokesman Bill McAllister would not comment on the arrest . `` This is not a state government matter , '' he said .
Sherry Johnston is the mother of Levi Johnston , boyfriend of Bristol Palin . The family has been in hiding since their home was raided by FBI agents on Monday morning and they were questioned about allegations that they had abused a young girl. Johnston is free on bail , scheduled for arraignment January 6 . Palin spokesman has no comment : `` This is not a state government matter ''