ST. JOSEPH — A person’s brain is not fully developed until the age of 25, and Allan Martin’s brain was not fully developed when he murdered a man in 1996, an expert in adolescent cognitive brain development testified Wednesday.

In his testimony, Dr. Daniel Keating told the court that childhood trauma intensives a teen’s impulsive behavior. Keating said he never personally evaluated Martin and does not have specific knowledge of the decades-old case, but based his opinion on scientific research.

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