DOVER, Del. — Defense attorneys in the fraud and conspiracy case against four former executives of Wilmington Trust Corporation are asking a federal judge to acquit them on all charges.

In court papers filed Friday, defense attorneys say that after calling almost two dozen witnesses and presenting volumes of exhibits over four weeks, prosecutors have failed to show that the defendants engaged in any conspiracy or wrongdoing.

Prosecutors say the former Wilmington Trust executives concealed the truth about the bank’s imploding commercial real estate loan portfolio before the century-old institution was hastily sold in 2011 while teetering on the edge of collapse.

The bank itself — the only financial institution to be criminally charged in connection with the federal bank bailout program — reached a $60 million settlement with prosecutors last year.