Boston Marathon bombing suspect Dzhokhar Tsarnaev's statements to police in his hospital room may be inadmissible in court.

In a May 7 pre-trial hearing, lawyers for the defendant argued that their client was not read his rights and was under the influence of painkillers when federal investigators interrogated him for 36 hours.

Tsarnaev was taken to the hospital in critical condition on April 19, 2013, after being shot in the head, neck, hand, and legs by police. Tsarnaev's lawyers said that 20 hours later, federal agents were questioning him regarding his involvement in the April 15 Boston Marathon bombings.

Dzhokhar Tsarnaev and his brother, Tamerlan, are accused of planting two bombs near the finish line at last year's marathon. Three people were killed and over 260 were injured, including over a dozen amputations. Tamerlan, 26, was killed during a firefight with police officers.

Tsarnaev, 20, was not informed of his right to an attorney under an exception that allows this omission when public safety is threatened. However, his lawyers stated in court documents that the hospital interrogation continued "despite the fact that [Tsarnaev] quickly allayed concerns about any continuing threat to public safety, repeatedly asked for a lawyer, and begged to rest".

The attorneys also said that the pain medication administered for Tsarnaev's gunshot wounds impaired his judgement.

During the interrogation, Tsarnaev told investigators how the pressure-cooker bombs were made, and what he and his brother were doing in the days leading to the attack. His attorneys said that he was denied representation and court appearances until he answered their questions.

The defense team also asked for the death penalty to be taken off the table, citing the recent botched executions in Oklahoma and Ohio.

Prosecutors are expected to file court documents countering the defense's statements.

Tsarneaev has pled not guilty to 30 federal charges, including using a weapon of mass destruction.