Without a little bit more guidance as to what part of the book this question is referring to, I am going to have to provide three different instances where I believe Judge Ford decides to do something to help solve the mystery of who killed Sam Westing.
The first possible answer to the question is that Judge Ford decides to throw a party for the heirs. The party does two things. It allows the various teams the opportunity to compare clues, but it also allows her team (and other teams) to spy on each other.
The party went on and on. No one dared be first to leave. (Safety in numbers, especially with a judge there.) So the guests ate and drank and jabbered; and they watched the other guests eat and drink and jabber. No one laughed.
The second possible answer is that Judge Ford hires a private investigator. She does this because she has realized that at least four of the heirs have specific Westing connections. She needs to find out more about those tenants and any others.
She would have to hire a detective, a very private detective, who had not been associated with her in her practice or in the courts.
The final possible answer is that Judge Ford agrees to act as the presiding judge for the court trial that Turtle Wexler calls for in order to figure out who supposedly killed Sam Westing.
Judge Ford rapped for silence with the walnut gavel presented to her by associates on her appointment to a higher court. Higher court? This was the lowest court she had ever presided at: a thirteen-year-old lawyer, a court stenographer who records in Polish, and the judge in African robes. Oh well, she had played Sam Westing’s game, now she would play Turtle’s game.