Premier Exhibitions, which brought the "Bodies Revealed" show to Sacramento in December, claims all the plasticized corpses come from individuals who donated their bodies to medical science.
The company says, however, bodies used in its other exhibits were unclaimed or unidentified bodies provided by a medical university in the Chinese city of Dalian.
ABC News 20/20 reporter Brian Ross travelled to China to speak to the president of the medical school, who denied a relationship with Premier Exhibitions.
"They don't give any bodies, they say, to anybody connected with putting them on display in the United States. They don't know about Premier Exhibitions," Ross said in a satellite interview with News10.
Ross said he found evidence that at least some of the bodies are those of executed prisoners bought in a thriving Chinese black market.
Assem. Fiona Ma, D-San Francisco, has authored legislation that would require exhibitors of human bodies to prove the corpses were donated.
"We need to better regulate these shows to make sure that these bodies are, indeed, donated," she said.
Ma's Assembly Bill 1519 has been approved by the state Assembly and awaits action in the state Senate.
In an e-mail, a spokesperson for Premier Exhibitions insisted, "All of the bodies and organ specimens in 'Bodies Revealed' came from individuals who chose to donate their bodies to accredited medical universities... for the purpose of study and education. All individuals died from natural causes."
The spokesperson goes on to say that 20/20's report only pertained to "Bodies...The Exhibition" which is also run by Premier Exhibitions.