Harvey Milam, whose father admitted to the racist murder that helped spark the civil rights movement, is accused of cheating investors out of millions of dollars

The son of one of the killers of Emmett Till, whose racist murder in 1955 helped spark the civil rights movement, is named in the Panama Papers leak of 11.5m files detailing the tax avoidance and financial affairs of thousands of people.

Harvey Milam – a Mississippi businessman and son of JW Milam, who admitted to the brutal murder of 14-year-old Emmett but was acquitted – is accused in the papers of cheating investors out of hundreds of millions of dollars.

Milam, who denies the claims that were settled in 2012 with no admission of wrongdoing, is among a fresh batch of Americans named in the papers. Others include Len Gotshalk, an Atlanta Falcons football player turned Oregon businessman who has faced fraud charges, and Martin Frankel, a Connecticut financier famed for his lavish lifestyle who pleaded guilty in 2002 to 20 counts of wire fraud and racketeering conspiracy.

Like Milam, Gotshalk and Frankel’s names appear on documents leaked from Mossack Fonseca, a Panama-based law firm that specialises in offshore financing.

They are among 36 Americans identified by the International Consortium of Investigative Journalists (ICIJ), which has been working with journalist partners including the Guardian to review the huge data leak, which has sparked public and political outcry across around the world.

Creditors of collapsed Caribbean insurance firm Condor Insurance, claimed Harvey Milam, and others, cheated investors by transferring the insurer’s assets to other companies. Milam did not respond to requests by the ICIJ for comment, his lawyer declined comment.

According to Mississippi’s Clarion-Ledger newspaper many of Condor’s $313m assets were transferreed to Condor Guaranty, a firm Milam reportedly worked to set up under the Bahamian Friendly Society which apparently offered services to members only.

“We could send out notices of the sale to all creditors etc. and really confuse the heck out of them,” Milam wrote in an 2006 letter, according to the Clarion-Ledger. “By then the … system will be up and running, and it will be time to buy a boat.”

The murder of Emmett Till was a galvanising event for the civil rights movement. Rosa Parks, who refused to give up her seat in Montgomery, Alabama, sparking the bus boycott that would kickstart the civil rights era, said Emmett was on her mind.

Emmett’s killing has been the subject of a play by the Nobel laureate Toni Morrison, a poem by the Harlem Renaissance writer Langston Hughes, and a song by Bob Dylan.

He was killed after apparently wolf-whistling at Carolyn Bryant, a white woman, in a grocery store. Her husband, Roy Bryant, and his half-brother JW Milam were so outraged they tortured and drowned him. Emmett’s body was fished out of the Tallahatchie river with a bullet in his skull, an eye gouged out, and his forehead crushed on one side.

Bryant and Milam were tried for murder in September 1955, but both men were acquitted after the all-white jury deliberated for barely an hour. In the knowledge that they were protected against further prosecution by the double jeopardy rule, the duo openly admitted to the murder in a magazine interview a year later.

“I’m no bully,” Milam told Look magazine. “I never hurt a nigger in my life. But I just decided it was time a few people got put on notice … ‘Chicago boy,’ I said, ‘I’m tired of them sending your kind down here to stir up trouble, I’m going to make an example of you, just so everybody can know how me and my folks stand.’”

The case was reopened by the FBI in 2004 to see if any accomplices could be brought to justice. But in 2007, a grand jury decided there was insufficient evidence to bring charges.