Prosecutors have dropped murder charges brought against a 21 year-old Dorchester man who was arrested and charged with the murder of a 67 year-old man in Codman Square last month. Kevin Williams was released from custody earlier this week after prosecutors said new evidence had surfaced in the case. Williams' family has since pressed for an apology and an explanation for why he was arrested and charged in the first place.

The case was prompted by the Oct. 6 murder of Jose Luis Phinn Williams, who was gunned down during an apparent robbery at the Fabian Gas Station on Washington Street near Dorchester courthouse. Kevin Williams— no relation to the victim— was arrested later that night based on what prosecutors and police said was video evidence and an eyewitness who pointed him out.

In a statement released Friday, Suffolk District Attorney John P. Pappas said the decision to was “the ethical step was to withdraw the charges prior to the first scheduled court date as that investigation continues.”

Prosecutors said Williams’ arrest was supported by a detailed description of the assailant by an independent percipient witness at the scene; a positive identification of Williams as the gunman; and corroborating video footage – circumstances that

Pappas' statement also said that "clearly supported probable cause" did exist for the initial charges. But, the DA's office said that "in the weeks that followed, detectives continued to seek and gather evidence from multiple sources, and prosecutors fought in court obtain potentially exculpatory evidence from Williams’ attorney and were forced to send grand jury subpoenas in order to obtain alibi testimony."

Pappas said that "expedited forensic testing" had also informed the decision to vacate charges because "they concluded that the evidence was insufficient to establish guilt or innocence and filed a nolle prosequi – a legal document withdrawing the charges."

“We don’t force the evidence to fit the case,” said Pappas. “We follow the facts wherever they lead, and today they led us to this decision. The investigation remains open, it remains active, and it remains a priority for us.”