The swift acquittal of two Bear Stearns executives in the government’s criminal case tied to the financial meltdown likely will force prosecutors to rethink the evidence they planned to present in a raft of cases that have yet to go to trial, legal experts say.

Criminal cases may be percolating against executives at fallen mortgage lender Countrywide Financial Corp. and bailed-out insurance giant American International Group Inc., among others. The Bear Stearns acquittals show how tough it can be to prove that bank executives committed fraud by lying to investors.