Defense lawyers said the government withheld the identities of the prosecution's main witnesses by allowing them to go by pseudonyms in the courtroom and wear disguises, thereby violating their client's Sixth Amendment right to confront his accusers.
"We were deprived of the opportunity to know who the operatives were, and to inquire into their backgrounds," Steven T. Wax, who served on Mohamud's legal team, said.
Government prosecutors deny the defense accusation and said they turned over all their evidence.
The (Portland) Oregonian said that since Sept. 11, 2001, protecting constitutional rights while also protecting the identities of those who testify has been difficult.
A jury found Mohamud guilty Thursday of attempting to detonate a bomb in Portland in 2010 during a holiday tree-lighting ceremony, The (Portland) Oregonian reported.
Mohamud faces a possible life term, and his sentencing is set for May 14, The Oregonian said.
Prosecutors said they haven't decided what sentence they will request.