By Sharon Coolidge
The Cincinnati Enquirer

Extremely low levels of a brain chemical, coupled with binge use of alcohol and drugs, made Eric Robinson fly into a rage and kill an elderly Sycamore Township man, his lawyers say.

Ohio law says Robinson's lawyers can't use that theory as a defense in his murder trial. But Norman Aubin and Mark Krumbein say if their client is convicted in the death of Harry Brown, 85, they'll present it as a mitigating factor in sentencing.

Hamilton County Prosecutor Mike Allen is seeking the death penalty.

A grand jury indicted Robinson on aggravated murder and aggravated robbery charges.

Krumbein said he'd ask Judge Norbert Nadel to allow the jury to consider less serious charges of murder and manslaughter.

Jury selection begins today. Aubin and Krumbein are expected to quiz potential jurors on what they know about serotonin, a mood-regulating chemical neurotransmitter in the brain that experts say is important in maintaining self-control.

The argument that low levels of serotonin played a role in killings has been used about a dozen times nationwide, with some success. In March 1999 after hearing how serotonin affects a person's mood, a jury sentenced a Dayton man convicted of killing his grandparents to life in prison instead of death.

"The theory is when a person is heavily under the influence (of alcohol or drugs), people with low levels of serotonin can completely lose control and go into a violent rage," Krumbein said. "It doesn't seem real to them."

Brown was paying Robinson to do odd jobs around his home in August 2002when he was beaten and robbed.

Robinson told authorities he doesn't remember anything until he was back in his van covered in blood.

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E-mail scoolidge@enquirer.com