Convicted drug dealer admits he shot Northeastern student to death in beef she had nothing to do with

Convicted coke dealer Cornell Smith, 33, pleaded guilty today to shooting Rebecca Payne to death in her Mission Hill apartment in 2008, the Suffolk County District Attorney's office reports.

Suffolk Superior Court Judge Jeffrey Locke sentenced Smith to 18 to 20 years in state prison for voluntary manslaughter - a sentence that will run concurrently with the 12-18-year federal drug sentence he is already serving for a Dorchester drug arrest three months after Payne's murder. Smith was on bail on another drug case when he shot Payne to death.

In court today, Smith admitted to charges that he went to Payne's building to shoot up a rival drug dealer he thought had ratted him out, but broke into the wrong apartment, mistook Payne for her and shot her repeatedly instead.

Smith had originally been indicted on a charge of first-degree murder; prosecutors agreed to the lesser charge in a plea bargain in part because of the unrelated death of a key witness last May. The investigation into Payne's death was initially hampered when none of her neighbors called 911 even after hearing the shooting, prosecutors say.

Prosecutors say they got a break last year in reviewing filings in the federal drug case against Smith:

Among those filings were letters that Smith had sent to the federal court in which he appeared to take responsibility for Payne’s homicide. Bradley relayed his findings the the homicide trial team.

In addition to “apologizing to the Paynes and the Balba family” in those letters, Smith wrote of his physical confrontation with the rival female drug dealer, “which was leading to the unfortunate passing of Rebecca Payne at the hands of I, Cornell Alan Smith, Sr.”

“The Payne family has spent seven years waiting, wondering if they would find justice for their daughter,” DA Dan Conley said in a statement. “Her killer’s unequivocal admission of guilt gives them a sense of finality and I hope this 20-year prison sentence provides some small measure of accountability in the face of their loss.”