“The Cowans case is just one of several wrongful convictions,” said O’Toole during a press conference last week at the Massachusetts attorney general’s office. “While I am somewhat relieved that no criminal charges will be filed against the Boston Police Department, I still am seriously troubled by this case.”

Attorney General Tom Reilly said that a months-long investigation conducted by his office had found no evidence to prove that fingerprint technicians Dennis LeBlanc and Rosemary McLaughlin were guilty of intentionally framing Cowans.

“No criminal charges resulted but that is not the end of the story,” said Reilly. “This absolutely should not have happened, and it is an inexcusable failure. It identified systemic and personal problems that will be and continue to be addressed.”

The grand jury’s failure to find sufficient evidence of conspiracy in the Cowans case has civil rights activists up in arms.

“I just think the justice department needs to look at that case and see whether or not there was any criminal conspiracy by any Boston Police Officer and the fingerprint division to convict an innocent person,” said Leonard Alkins, president of the Boston Branch of the NAACP.

Alkins said there should be an independent commission established, composed of legal scholars and prosecutors, to look for other wrongful convictions over the past 25 years.

“I think they haven’t really seriously looked at the problem of wrongful convictions,” he said. “I think that there have been too many wrongful convictions overturned recently, especially involving the policies and procedures of the Boston Police.”

In May, the Boston Herald reported that at least 22 men had been wrongfully convicted in Massachusetts over the past two decades. Most of the men were black, and most were investigated by the Boston Police.

The Boston Police homicide unit has been criticized for over-aggressive interrogations and for focusing their investigations too narrowly on one suspect once a suspect is found.

The men found to be wrongfully convicted served as many as 19 and a half years behind bars before being released.

Activists say that too often Boston police officers arrest suspects despite weak evidence, and then the courts take the cases before suspects can sue for false arrest.

“Even if they know the arrest is shoddy, they will go forward on the slimmest evidence, knowing the defendant doesn’t have the resources for proper representation in a circumstantial case.”

Police officers should be held accountable for shoddy investigations that lead to wrongful convictions, according to Kazi Toure, co-director of the Criminal Justice Program at the American Friends Service Committee.

“I think if they prosecuted those officers whose work led to the wrongful convictions, and started looking into prosecuting misconduct, that would deter other cops from doing it in the future,” said Toure. “They are just sending a statement that it is ok for cops to do this.”

Activists also blame underfunding of the public defender system which they say leads to overworked and underpaid defense attorneys eager to convince their clients to go in for a plea bargain even if the clients know they did not commit the crime.