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A federal jury on Monday convicted an Arkansas doctor of masterminding a bombing attack against the head of the state medical board last year, despite the absence of forensic evidence tying the defendant to the crime.

Dr. Randeep Mann could be sentenced to life in prison for his role in the attack on Dr. Trent Pierce outside of Pierce's West Memphis home on Feb. 4, 2009.

Prosecutors say Mann was bitter at the board for repeatedly sanctioning him for over-prescribing prescription pain medication, so he decided to exact revenge on Pierce. They told jurors they don't believe Mann planted the bomb in Pierce's driveway, disfiguring and partially blinding Pierce, but that they believe Mann put someone else up to it. They haven't charged anyone with planting the bomb.

Prosecutors admitted during the trial that extensive testing of materials taken from the crime scene — a spare tire, a hand grenade, duct tape and a piece of string used to pull the pin — showed no match to materials found in and around Mann's Pope County home some 200 miles away. So they relied on witness testimony about Mann's anger toward the board and his propensity for collecting military-grade weaponry to convince jurors Mann planned the attack.

"In this case it was difficult, however we had a lot more evidence than just forensic evidence," assistant U.S. attorney Karen Whatley said after the jury convicted Mann of seven of the eight charges he faced, including the most serious — using a weapon of mass destruction. "You don't have to have forensic evidence every time you try a case, and I think the jury understood that."

Among the strongest pieces of evidence prosecutors presented was 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 Mann's had an Altima from which the spare was missing when federal agents executed a search warrant.

A friend of Mann's also testified that the doctor repeatedly said members of the Arkansas State Medical Board needed to suffer like he suffered. And a weapons dealer testified that he sold Mann — himself a registered federal firearms dealer — the type of grenade used in the attack, though defense attorneys later attacked the dealer's credibility.

Mann's attorneys say the case is ripe for appeal and that they hope the 8th U.S. Circuit Court of Appeals at St. Louis reverses the verdict based on a lack of evidence connecting Mann to the crime.

"We have an abiding conviction that the evidence in this case is legally insufficient to support this jury's verdict," defense attorney Blake Hendrix said.

Hendrix said he'll appeal after Mann is sentenced, which will happen after a pre-sentence report is completed, typically within 60 to 90 days. He said the appeal will contend that there wasn't enough evidence to connect Mann to the bombing, which detonated when Mann was at home.

The jury deliberated for a little over two days before delivering its verdict. In addition to the weapon of mass destruction charge, Mann also was convicted of destroying a vehicle with an explosive, obstruction of justice and illegally possessing 98 grenades and a machine gun. He was acquitted of illegally possessing a shotgun.

His wife, Sangeeta "Sue" Mann, was convicted of obstruction of justice but acquitted of lying to a grand jury.

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

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

One of the couple's sons began loudly crying 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. Her husband gently rubbed the back of her head with his hand.

Mann's family declined to comment after the verdict, and no number was listed for their home in London, Ark. Pierce's wife, Melissa, and their lawyer, Betsy Murray also declined to comment. Pierce was not in court Monday because he was seeing patients in his West Memphis medical clinic, and his attorney said he would not comment on the verdict.

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 painkillers and other addictive drugs. 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 was initially arrested after 98 grenades were found buried in a clearing near his rural Pope County home. He was convicted of possessing those grenades, as well as an unregistered machine gun. The doctor had more than 100 firearms in gun safes in his home, but only two were found to be unregistered when federal agents executed a search warrant in March 2009.

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Associated Press Writer Chuck Bartels contributed to this report.