The U.S. Drug Enforcement Administration is investigating where Los Angeles Angels pitcher Tyler Skaggs obtained the drugs that were in his system at the time of his July 1 death in Southlake, Texas, two sources with knowledge of the investigation told Outside the Lines on Wednesday.

An autopsy released Aug. 30 found evidence of fentanyl, oxycodone and ethanol in Skaggs' system. The fentanyl drew the attention of federal investigators, the sources said. One senior DEA official said the agency typically gets involved in fentanyl cases in an effort to track down the source of the drug.

Fentanyl, a powerful synthetic opioid, has been linked to a number of high-profile drug-related deaths, including musicians Prince, Tom Petty and Mac Miller.

Skaggs was found dead in his hotel room July 1 during a road trip against the Texas Rangers, having choked on his own vomit.

One federal law enforcement agent, speaking on condition of anonymity, said fentanyl has been showing up "everywhere, even in marijuana."

"We continue to cooperate with law enforcement on this important matter," Angels team spokesperson Marie Garvey said.

MLB deputy commissioner Dan Halem declined comment. Attorney Rusty Hardin, who represents Skaggs' family, did not return messages seeking comment.

When the Tarrant County Medical Examiner's office released its autopsy report, Skaggs' family issued a statement saying, "We were shocked to learn that it may involve an employee of the Los Angeles Angels. We will not rest until we learn the truth about how Tyler came into possession of these narcotics, including who supplied them."

No team employee has been publicly identified as having been connected to Skaggs' death, or as a target in the investigation.