Moore has an extensive criminal history, according to court documents, including convictions for two separate assaults on corrections officers committed while he was imprisoned on another unrelated conviction. Prosecutors also said that Moore plotted to kill a prosecutor handling this case.

Jane Loving, who represented Roach, noted that other defendants in the case who were more closely involved in the shootings but had pleaded guilty, received comparably shorter sentences. She asked the judge to impose a term of forty years.

And Garland Sanderson, an attorney for Chisholm, said that his client had only a tangential role in the conspiracy and had been influenced by older people he considered family. He said Chisholm — who had no prior criminal record as an adult — also was young enough that he could still turn his life around.

He asked for a sentence of life with all but 10 years suspended, but Brown followed the prosecution's recommendation.

"You say your client had a minor role," Brown said, "but he played a minor role in a major, criminal, tragic event in the community."

Prosecutors made the same point in court documents. They urged the judge to impose stiff sentences on all the defendants and recommended a term for Chisholm that fell outside the usual guideline range, because the guidelines "do not contemplate this type of charge and accordingly should not be the sole guide for the court in imposing a just sentence."

But in the memo, prosecutors saved their harshest words for the head of the conspiracy.

"Robert Moore is a dangerous man who, as part of a personal vendetta, has been found guilty of serial acts of extensive violence," prosecutors wrote. "Moore was the architect of this reign of terror that he unleashed against Alex Venable, his family and their associates. Driven by vengeance, Moore took on the roles of judge, jury and executioner."

Baltimore Sun reporter Ian Duncan contributed to this article.