LONDON—Scottish lawmakers have demanded the country’s government release full details of the medical advice that led to the release from jail of the Lockerbie bomber almost a year ago.

Opposition Labour Party legislators called for the prognosis made of Abdel Baset al-Megrahi’s health before he was freed on compassionate grounds—and the names of the doctors who made the assessment—to be made public.

The contentious decision to release al-Megrahi from a Scottish prison has stirred anger in the United States, and prompted U.S. senators to begin an investigation into the circumstances behind the decision.

Al-Megrahi is the only person to have been convicted over the 1988 bombing of a jetliner above the small town of Lockerbie, Scotland, which killed 259 people—mostly Americans—on board the plane, and another 11 on the ground.

He was convicted in 2001 and sentenced to serve a minimum of 27 years in a Scottish prison, but in 2008 was diagnosed with terminal prostate cancer.

James Kelly, community safety spokesman for the Labour Party in Scotland, said the Scottish government’s justice secretary Kenny MacAskill must disclose the medical advice which led to al-Megrahi being freed.  “It’s time that Kenny MacAskill released the full facts surrounding the medical evidence of al-Megrahi’s release,” he said in a statement.

Kelly said some recent medical studies contradict the claim made at the time of al-Megrahi’s  release last August that he may only survive for around three months.  “We know that al-Megrahi intended to start chemotherapy—he indicated that in his application for release,” Kelly said. “It’s now time for the full facts to come out.”

Scotland has had a separate government with responsibility for some decision-making and local taxes since 1999. However, the British government in London controls all policy effecting the entire U.K., foreign policy and defense.

The head of the Catholic Church in Scotland on Sunday defended the release of al-Megrahi, claiming that the Scottish justice system had a proudly held “culture of compassion.”

“On the other hand, there still exists in many parts of the U.S., if not nationally, an attitude towards the concept of justice which can only be described as a ‘culture of vengeance’,” Cardinal Keith O’Brien wrote in the Scotland on Sunday newspaper.

He criticized the decision of the U.S. Senate Committee on Foreign Relations to investigate al-Megrahi’s release. Both the Scottish and British governments have declined requests to send ministers to a planned hearing on the case.

“I would rather live in a country where justice is tempered by mercy than exist in one where vengeance and retribution are the norm,” O’Brien wrote.