Updated

LITTLE ROCK, Ark. -- An Arkansas doctor accused of seeking revenge on a state medical board that repeatedly disciplined him was found guilty Monday of masterminding a homemade bomb attack that disfigured and partially blinded the board's chairman.

A federal jury convicted Dr. Randeep Mann, 52, of using a weapon of mass destruction and destroying a vehicle with an explosive in the February 2009 attack that nearly killed Dr. Trent Pierce. Mann, a federal firearms dealer, also was convicted of illegally possessing 98 grenades and a machine gun. He was acquitted of illegally possessing a shotgun.

He faces up to life in prison for the weapon of mass destruction charge when he is sentenced on a later date.

Before the verdict was read, Mann smiled at his children and other family members who were watching from the courtroom gallery. He and his wife, Sangeeta "Sue" Mann, who was also on trial, spoke quietly to one another before hearing the jury's decision, as they had throughout the five-week-long trial.

One of Randeep Mann's sons began loudly sobbing when the first guilty verdict against his father was read. Other family members began crying as the drumbeat of guilty verdicts continued.

As jurors were filing out of the courtroom, Sue Mann collapsed into her chair, but she remained conscious. Her husband gently rubbed the back of her head with his hand.

U.S. District Court Brian Miller allowed Sue Mann to remain free on bond pending her sentencing. Her husband was ordered to remain behind bars.

Prosecutors acknowledged having no forensic evidence connecting Mann to the bomb scene or proving he planted the explosive -- made from a hand grenade duct-taped to a spare tire -- in Pierce's driveway in West Memphis.

Defense attorneys argued investigators targeted the wrong person because of the family physician's race and his love of weapons collecting.

Still, prosecutors argued, there were links, including an e-mail Mann sent to his brother in India with the subject line "Pierce" and a photograph of the doctor, with the text, "I hope this picture is good." The bomb itself was made from a spare tire from a 2002 Nissan Altima, and prosecutors said a friend and business partner of Randeep Mann's had an Altima from which the spare was missing when federal agents executed a search warrant.

A friend of Randeep Mann's also testified that the doctor repeatedly said members of the Arkansas State Medical Board needed to suffer like he suffered.

Pierce, whose face remains speckled with bits of black tire still lodged in his skin from the bombing, led the panel that sanctioned Mann after complaints he was over-prescribing pain pills to known drug addicts. The board revoked Mann's right to prescribe narcotics after complaints that 10 of his patients overdosed and died.

At the time of the bombing, the board was investigating whether Mann was continuing to prescribe controlled substances, despite the revocation of his Drug Enforcement Agency permit to do so.

Mann's attorneys argued the case was circumstantial at best.

Mann and his wife also were convicted of obstruction of justice charges. She was acquitted of lying to a grand jury investigating the case.