The former Chilean dictator Augusto Pinochet stowed away more than $13m (£6.8m) in 125 bank accounts, according to a US Senate investigation.
The general's financial dealings are coming under further scrutiny
It found a range of top banks helped Gen Pinochet hide his funds or broke regulations over his accounts.
Bank officials say the accounts were opened under false names and have vowed to co-operate with investigators.
Gen Pinochet's military regime killed and tortured thousands of political prisoners in the 1970s and 1980s.
He is also being investigated in Chile over allegations of human rights abuses and embezzlement of state funds.
Web of accounts
The senate investigation revealed Gen Pinochet and his family members used scores of bank accounts to hide and launder funds over the course of at least 25 years.
It found some of the banks allowed the general to use assumed names on accounts, arranged international wire transfers and set up offshore companies.
Among the institutions named in the report are Bank of America, Coutts, Riggs Bank and the world's largest financial services group, Citigroup.
"Some banks actively helped him hide his funds, others failed to comply with US regulations requiring banks to know their customers," Democrat Senator Carl Levin said.
All of the accounts have since been closed.
The report said Gen Pinochet's suspicious dealings with Washington-based Riggs Bank spanned 25 years, rather than the eight-year period for which it has already paid a fine.
In January, Riggs Bank pleaded guilty to failing to report suspicious activity relating to accounts held by Gen Pinochet and the government of Equatorial Guinea.
The bank later agreed to pay $8m to victims of crimes committed during his regime.
The BBC's Ian Pannell in Washington says there will now be pressure on the others to do likewise.
In a statement, Citigroup said its accounts for the general were opened "with false documentation using pseudonyms".
Bank of America, for its part, said it had "co -operated fully with the subcommittee in its investigation, conducted a thorough internal investigation and submitted documents as requested".