BELLINGHAM, Wash. — Editor's note: The above video previously aired on KING 5 about the number of fentanyl overdoses increasing. 

Federal prosecutors are warning people in the Bellingham area that street pills could be tainted, after a woman who took them died.

An investigation began Monday after a woman was found unresponsive at a home on the Lummi Indian reservation. The overdose-reversal drug naloxone was unsuccessful and the woman died, according to a news release from Seattle U.S. Attorney Brian Moran's office Tuesday. 

The pills appear to be oxycodone but are undergoing lab testing to determine whether they are tainted with fentanyl or other substances.

Authorities arrested Tony Lee Williams, 33, on Tuesday, saying he allegedly sold some of the tainted pills. Police also found cocaine and heroin in his apartment, according to court documents. 

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Williams is charged with possession of cocaine and heroin with the intent to distribute. 

According to court documents, Williams allegedly sold the pills to a brother and sister who distributed them to others. 

Prosecutors said they believe the pills were sold on the Lummi reservation and to people who are connected to nightclubs in Bellingham. 

"It is critically important that the word go out about these potentially deadly pills," said Moran. "Right now, we don't know whether the pills are directly connected to the death. However, anyone buying street pills that appear to be oxycodone 30s, like those described in this case, could be risking his or her life by ingesting them." 

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