Police in Lucca, Italy arrested six people in connection with the death of Linas Rumsas, 21, the son of Lithuanian former professional Raimondas Rumsas.
The detained included the Altopack-Eppela team owner Luca Franceschi and directeur sportif Elso Frediani, former trainer Michele Viola and pharmacist Andrea Bianchi, who have been accused of supplying prohibited substances to riders.
Linas Rumsas died of a heart attack on May 2, 2017.
"Since the young man, in the weeks leading up to his death, had obtained excellent placings in particularly tough races, far superior to those obtained in the past, the suspicion immediately arose that the sudden death was due to the use or abuse of unauthorized drugs," police said, according to AFP.
The family had a history of run-ins with authorities for doping. Raimondas Rumsas' wife Edita was detained in 2002 after police found her with a camper van carrying loads of banned drugs after he finished third in the Tour de France. In 2003, he tested positive for EPO at the Giro d'Italia and served a one-year ban. In 2006, they received a suspended four-month sentence for importing prohibited drugs.
The police said the investigation uncovered a "real partnership aimed at facilitating doping practices," and that the team owner Franceschi "recruited the most promising cyclists, motivated them to take drugs and procured doping substances for them, including EPO in microdoses."
After the death of Linas Rumsas, the doping allegedly continued but was moved to the home of Francheschi's parents, who allowed riders to store and use EPO, opioid painkillers and other drugs.
In addition to the six who remain under house arrest, 17 more people are being investigated in connection with the doping scheme.