IOWA CITY, Iowa (AP) — Investigators believe a letter purporting to be from a juror who was bribed to rule for the University of Iowa in a major medical malpractice case was likely a hoax by someone upset with the verdict. Johnson County Lt. Doug Gwinn says his 20-month investigation into the letter’s shocking allegation of jury tampering has turned up no evidence that a bribe occurred. He says he’s been unable to identify the author of the letter but believes it was someone who wanted to help the plaintiffs get a new trial.

A judge received the anonymous letter after a February 2016 trial in which parents sued UI Hospitals and Clinics for brain damage suffered by their child during birth. Jurors ruled that UIHC was negligent but awarded no damages.