The proverbial barn door slams shut too late. The horses are long gone.

Pennsylvania will audit the management of its two big pension funds amid a federal investigation into the fees paid to outside firms that invest billions of taxpayer dollars.

Just four days earlier, federal prosecutors announced charges against former state Treasurer Barbara Hafer and businessman Richard Ireland, whose firm marketed the services of private investment managers and shared in the fees, which amounted to millions.

Hafer, 72, of Indiana, Pa., was charged with two counts of making false statements to federal agents when she was asked about payments of $500,000 to her consulting firm. Prosecutors said the payments began within weeks of Hafer leaving office in 2005, but they did not say whether they think Hafer did anything wrong while in office.

On Monday, state Auditor General Eugene DePasquale said his office intends to audit the management of $78 billion in assets by the Public School Employees’ Retirement System and the State Employees’ Retirement System.

DePasquale insisted the timing is coincidental, and that the charges against Hafer did not motivate or even hasten the PSERS and SERS audits. But he did suggest that the auditors will give particular scrutiny to the fees paid to private investment managers.

The fees are huge. PSERS paid $455 million in investment fees last year; SERS paid $159 million and the state Treasury Department paid $12 million.

All of SERS’ nearly $26 billion in assets were invested by private firms, while the Treasury Department and PSERS manage some cash pools in-house.

It’s one thing to audit these massive retirement funds; it’s another to audit the expenses associated with the funds’ management.

It’s the only measurable reply to DePasquale’s rhetorical question: “We’re paying them a lot of money. What are we getting in return?”

The perception is that nobody in control really knows how well or how poorly the private managers of these billions of invested public dollars are performing, or to what extent they’re earning their fees.

Hafer didn’t care, if the criminal allegations are proven. Neither did her successor, Rob McCord, who already pleaded guilty to federal charges attempted extortion.

Serious reforms are needed to remove not only the opportunity to cheat the system but also the temptation to do so.

Last year, Gov. Tom Wolf sought to shave $200 million a year off the fees paid by SERS and PSERS. No bill to carry that out has come up for serious consideration.

Let’s hope the results of the audit that’s about to take place will provide the information needed to push Wolf’s proposal into law.

The people’s money should not be squandered — or stolen.