Fitchburg woman arrested on drug trafficking charges, over 300 grams of heroin/fentanyl seized

Authorities arrested an alleged Fitchburg heroin and fentanyl trafficker Tuesday afternoon and seized more than 300 grams of a heroin/fentanyl mixture, officials said.

Rosemary de los Santos, 29, of Fitchburg is facing multiple charges. She was arrested at about 2 p.m. Tuesday in a parking lot on Whalon Street in Fitchburg following an investigation, State Police said in a statement.

After the arrest, State Police executed a search warrant at her apartment on Depot Street, where a K-9 “showed interest in several locations,” State Police said.

Authorities found quantities of the heroin/fentanyl mixture, several grams of cocaine, and several OxyContin pills, State Police said.

Over the course of the investigation, over 300 grams of heroin/fentanyl were seized, State Police said.

Fitchburg police and the US Drug Enforcement Administration assisted with the investigation.

De los Santos was arraigned Wednesday at Fitchburg District Court where her bail was set at $10,000, Worcester County district attorney’s office spokesman Timothy Connolly said. Her next court appearance is set for June 18 for a probable cause hearing.

She faces three counts of trafficking in fentanyl, two counts of trafficking in heroin/morphine/opium, one count of possession of cocaine with intent to distribute, and one count of possession of OxyContin with intent to distribute, State Police said.

Breanne Kovatch can be reached at breanne.kovatch@globe.com. Follow her on Twitter at @breannekovatch.