Relatives of more than 50 people who died from contaminated fentanyl supplied to Argentina's hospital system protested outside the Italian Hospital in La Plata on Thursday, a city in Buenos Aires province, 60 kilometers south of the capital.

The relatives criticized that, after three months of investigation, the justice system has yet to formally press charges against those responsible for distributing the adulterated analgesic.

The federal court in La Plata, which is leading the current investigation, is looking into up to 100 suspicious deaths, 54 of which have been confirmed by independent experts provided by the families.

In early May, Argentina's Ministry of Health detected an infection from fentanyl contaminated with K. pneumoniae type MB and Ralstonia spp. bacteria in patients who had died or were in serious condition in hospitals in several provinces.

Health authorities determined that local firms, HLB Pharma Group and Ramallo Laboratories, had distributed the contaminated fentanyl and ordered the withdrawal of the contaminated batches from the market.

Additionally, they suspended the activities of both firms.

The justice system then ordered numerous raids on laboratories and drugstores, but so far, no one has been charged in connection with the events.

Fentanyl is a synthetic opioid primarily imported from China. It's used as an analgesic to control severe pain in patients in areas like intensive care or operating rooms.

Considered 50 times stronger than heroin, its recreational use is highly addictive and has proliferated across the continent.

AP Video shot by Victor R. Caivano