The investigation into the infamous murder of three young activists which became known as the "Mississippi Burning" civil rights case has finally closed after 52 years, the US state`s attorney general said Monday.
The three young men -- two Jewish and one black -- were executed in June 1964 in the midst of the "Freedom Summer" voter registration project. They had ventured south from New York to register African American voters.
The brutal killings of James Chaney, 21, Andrew Goodman, 20, and Michael Schwerner, 24, rocked the nation and went on to inspire the Alan Parker film "Mississippi Burning" in 1988.
"I am convinced that during the last 52 years, investigators have done everything possible under the law to find those responsible and hold them accountable," said Attorney General Jim Hood.
"There is no likelihood of any additional convictions."
At the time of the killings, the US Justice Department -- aware it had no chance of securing murder convictions faced with segregationist state authorities and all-white juries -- chose to prosecute the case under civil rights law.
In 1967, eight suspects received prison sentences -- serving less than six years in prison -- for federal civil rights violations connected to the murders.
Four decades on, in 2005, Hood and the county prosecutor won a manslaughter conviction against white supremacist Edgar Ray Killen, a former Ku Klux Klan (KKK) member who is currently serving a 60-year-prison sentence.
The night the activists disappeared, on June 21, 1964, local police -- allegedly infiltrated by the KKK -- arrested them on false pretenses, releasing them late that evening.
Shortly after the men left city limits, KKK members ambushed and shot them dead at point blank range. An FBI investigation uncovered their bodies 44 days later in an earthen dam on the secluded property of a Klansman.
The active federal and state investigation closed after the Justice Department found that no viable prosecutions remained, closing a significant chapter in Mississippi`s history, said Attorney General Hood.
"Our state and our entire nation are a much better place because of the work of those three young men and others in 1964," he said.
"We should all acknowledge that our diversity is this state`s greatest asset."