Updated

Lawyers for a doctor accused of masterminding a bombing that disfigured the chairman of the Arkansas Medical Board opened their defense Friday, hoping to show that prosecutors "cobbled together" a theory when they couldn't link the physician to the bomb or the scene.

Fingerprints found on bomb fragments don't belong to Dr. Randeep Mann and an eyewitness says a man she saw near the chairman's car before the explosion wasn't the man who's now on trial. The government hopes jurors will connect the dots in a puzzle that includes a little bit of a picture here, another fuzzy portion there.

Prosecutors say Mann was motivated by revenge to attack Dr. Trent Pierce outside the chairman's West Memphis home. The medical board took away Mann's right to prescribe addictive narcotics after hearing complaints that several of his patients died. At the time of the bombing, the board was investigating whether Mann continued to distribute controlled substances after its decision, which could have led to Mann losing his medical license.

And in its case the government noted Mann's access to weapons. Mann owns a million-dollar collection of guns and other weapons, including two launchers he sometimes used to fire practice grenades into the lake behind his home. The bomb used in the attack was made from an MK3A2 hand grenade duct-taped to a spare tire.

Defense lawyer Jack Lassiter called the prosecution's case "cobbled together to create a theory about this bombing. These circumstances could be rearranged to reach another theory."

Prosecutors acknowledged in their opening statement that they couldn't prove Mann planted the bomb, and they haven't charged anyone with aiding Mann in the attack.

"You won't hear any person say they saw him," prosecutor Karen Whatley told jurors.

But they have plenty of circumstantial evidence. A grenades manual was found in Mann's home, a friend said Mann told him he wished he could kill board members, and Mann once e-mailed a photo of Pierce to his brother. A jail inmate testified that Mann offered him $50,000 to kill Pierce.

"This case is not complicated. It is a case about a man ... who was intent on harming someone else based on what he had available to him," Whatley said.

Felecia Epps, a law professor at the University of Arkansas at Little Rock, said it would be unusual but not unprecedented for juries to convict defendants with little or no forensic evidence. She said prosecutors have moved slowly during the trial, trying to build their case "bit by bit."

"If you took (the evidence) in isolation, they sounded as if they didn't show a lot about the case — in some instances barely relevant. If you add them all together, they add them up to something," Epps said. "When prosecutors have cases like this, the jury's the one who has to be convinced beyond a reasonable doubt and they may not be willing to make the inferences they're being asked to make."

Pierce, his face scarred and embedded with bits of tire, testified this week that he lost an eye, his sense of smell, teeth and some hearing in the attack Feb. 4, 2009.

Mann was arrested a month later, but not initially for the bombing. It came after a municipal worker found a cache of grenades in the woods near Mann's home, and investigators later found more than 100 guns in his house including two that prosecutors said were unregistered.

Mann was a licensed federal firearms dealer, and defense attorneys say all of his weapons were legally registered. But prosecutors said he was not authorized to possess the grenades.

A tire was also found during the search of his home, in a bathroom's stand-up shower. Mann's wife said he was cleaning the tire, part of maintaining his prized car collection, but federal agents said it was bizarre and suspicious.

Prosecutors ultimately won an indictment alleging Mann planned the bombing to retaliate against Pierce because of his position on the medical board.

Witnesses said the grenades found near Mann's home were different from the one used in the bombing, but prosecutors are relying on testimony that Mann was a weapons nut who could have easily acquired an MK3A2 grenade.

Mann's longtime friend, Gerald Riley, told jurors that Mann repeatedly complained about the medical board, once saying he wanted to "kill those (expletive)." Gerald Riley also said Mann wondered aloud whether the bombing was justified.

Riley said Mann asked him, "Did you ever think that the explosion, the bombing, did exactly what it was supposed to do? It was supposed to make the person suffer."

Mann is charged with the bombing and with possessing unregistered grenades and several illegal firearms. His wife, Sangeeta Mann, is being tried for allegedly lying to a grand jury and obstructing the investigation. Both have pleaded not guilty.

Mann faces up to life in prison if convicted on the bombing charge.