In the DOJ letter, federal agents accuse the village police of repeatedly failing to cooperate with auditors and refusing to turn over key records during the probe.

Bal Harbour, which leads a task force with the Glades County sheriff’s office, helped seize $56 million in just three years — 2008 to 2011 — “without adequate written policies or procedures, prosecutorial oversight, or audits of undercover bank accounts,” said the DOJ.

The DOJ blasted Bal Harbour for tapping into $709,836 to pay employees salaries and benefits, despite strict federal bans on such practices.

Hunker told The Herald last week that all payments were approved by Treppeda and the village’s lawyers, Richard Weiss and Doug Gonzales.

In addition, DOJ cited findings by Bal Harbour’s independent auditor that revealed dubious expenses, poor record-keeping, and a lack of controls.

Because of the findings, the village is now forced to return $3.1 million — the village’s cut of the seized drug money in fiscal 2011 — $407,969 in additional proceeds, and another $709,836 in money that was not supposed to be spent on salaries and benefits.

Treppeda said the village has only about $2 million left in seized cash.

The investigation comes after years of Bal Harbour showcasing the goods it purchased with forfeiture funds, including $100,000 for a 35-foot boat powered by three Mercury outboards, $108,000 for a mobile-command truck equipped with satellite and flat-screen TVs, and $21,000 for an anti-drug beach bash.

In addition to the federal probe, other questions continue to nag the police about secret bank accounts funded with money from an entirely different pot: thousands paid by drug dealers to undercover cops to launder money and transport drugs.

The Miami Herald’s lawsuit is seeking records of how those monies are used, including credit-card expenses for flights and hotels — and cops fronting cash to snitches.

Brian Mulheren, a village resident and director of the Bal Harbour Citizens Coalition, said the group wrote a letter to U.S. Attorney General Eric Holder on Tuesday demanding a federal monitor to review the police department and the vice squad’s forfeiture program.

“This is the most disgusting, disgraceful, despicable thing that could ever happen,’’ Mulheren said. “We want our village to be clean and honest, and the public officials we have obviously allowed this to occur.’’

It is unclear how long Bal Harbour PD’s ban from participating in the federal program will last. Another uncertainty is where Bal Harbour will find the money to return $4.2 million to the feds.