Steven Kozicki said his client, Shaba-na Ansari, was interviewed by Chicago detectives for more than four hours and answered all their questions, the Chicago Tribune reported Wednesday.
The death of her husband Urooj Khan, 47, in July was re-classified a homicide after toxicology tests showed he had ingested a lethal amount of cyanide.
Authorities said they plan to go to seek court approval to exhume Khan's remains.
"I feel a complete autopsy is needed for the sake of clarity and thoroughness," said Cook County Medical Examiner Stephen J. Cina.
Ansari, 32, told the Chicago Sun-Times that she had nothing to do with her husband's death and was eager for investigators to dig up his body to learn the truth.
She also said she's given investigators access to the chemicals used in the family's dry cleaning business which doesn't include cyanide.