Police now have a $50,000 reward fund and new tips to help in their investigation into a bombing that critically injured the head of the Arkansas State Medical Board a month ago, authorities said Wednesday.

The U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives announced it would offer $20,000 for information leading to the arrest and conviction of the person who planted the homemade device that injured Dr. Trent Pierce outside his West Memphis home. That money, coupled with funds raised locally, pushes the total reward fund to $50,000, West Memphis police Chief Robert Paudert said.

"We think this will help. We think it will generate some calls — some good, some not so good," Paudert told The Associated Press.

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Paudert did not release new details about the attack but said detectives "got some very good information that's come forward this week."

Pierce, 54, remains in critical condition at the Regional Medical Center in Memphis, Tenn., across the Mississippi River from the town of West Memphis. Pierce, once unable to talk because of an oxygen tube in his throat, spoke once last week with ATF agents and will speak to them again, Paudert said.

Pierce was injured Feb. 4 by the blast that occurred when he reached down to move a stray tire from the path of his hybrid Lexus sport-utility vehicle, family friends have said. While ATF agents have declined to discuss the tire, they say the bomb was homemade.

Pierce lost his left eye in the explosion and suffered severe burns. He has undergone several operations and skin grafts, but can now sit up in a chair and read off of index cards, Paudert said.

Pierce leads the state Medical Board, which regulates doctors, therapists and osteopaths in Arkansas.