LONDON — Ayman al-Zawahri, al-Qaida's No. 2. George Habash of the PLO. Mahmoud Zahar, the Hamas strongman in Gaza. All trained as doctors, as did nearly all of the suspects in the failed bomb attacks in Britain.

The public often is shocked to see that doctors — the world's healers — can become militants or even terrorist killers.

But some experts believe it is part of a trend in which wealthy families educate their sons well, and those sons sometimes become radical and have the education needed to become leaders.

At least five of the eight suspects in the failed terrorist attacks in London and Glasgow, Scotland, were identified as doctors from Iraq, Jordan, Lebanon and India, while staff at a Glasgow hospital said two others were a medical student and a junior doctor. One was a medical assistant. All eight are believed to have worked for Britain's National Health Service.