STOCKHOLM (AP) — Swedish prosecutors say the investigation against a disgraced Italian stem cell scientist suspected of involuntary manslaughter in connection with three patients who died after windpipe transplants has been abandoned.

Prosecutor Jennie Nordin says it can't be proven that Dr. Paolo Macchiarini would be guilty of either causing another's death or causing bodily harm, so he is no longer a suspect.

Nordin told a news conference Thursday that "we have been unable to prove that any crimes have been committed."

Macchiarini was fired from Sweden's prestigious Karolinska Institute in March 2016 for breaching medical ethics after being accused of falsifying his resume and misrepresenting his work. His work was once considered revolutionary.