Investigators think Dominguez may have represented some of the fentanyl pills as being oxycodone, which is a far less potent and less dangerous drug compared to fentanyl.
Two Cheyenne residents, charged in separate drug cases, have been sentenced to federal prison, the United States Attorney's Office announced Wednesday.
Officials with the Larimer County Sheriff's Office say four people have been arrested and hundreds of fentanyl pills and other drugs found in recent arrests in southwest Fort Collins.
Opioids in general are more likely to cause overdose deaths than other drugs such as meth and cocaine, and because fentanyl is so powerful it poses an especially high risk.