The Golden Spiders: A Nero Wolfe Mystery

Nero Wolfe is seated at a large dining table. Archie comes in and joins him. He tells Wolfe he is overdrawn. Wolfe chides Fritz for changing one of his favorite dishes, but Archie enjoys it.Pete Drossos, a young boy, comes to the door, wanting to see Wolfe. He says he has a case, and Archie invites him in. He is a window washer and has seen a woman being abducted. The woman had a golden spider earring. Wolfe instructs Archie to call Cramer to have him trace the car, and the boy leaves to get his lunch.The next day, Stebbins comes to the door. Pete has been killed in a hit and run by the same car. While they discuss the case, Pete's mother comes. Before he died, he had told her to give Wolfe all his money to have Wolfe find his killer.They use the small amount of money he had to run an ad in the paper attempting to draw in the murderer. When he sees it, Cramer comes to find out why, and they discuwo ss Matthew Birch, another man found dead in an alley the previous day. Evidence suggests the same car that killed Pete Drossos also killed Birch.A woman calls at the brownstone, in response to the ad. She is wearing the golden spider earrings. She refuses to give her name, but wants to see Pete. Wolfe forces her to reveal her name, Laura Fromm. She writes Wolfe a check for $10,000 for his advice and help, and promises to return the next day. She refuses to identify the woman in the car.The following day, two lawyers, Denis Horan and Bernard Levine, appear to tell Wolfe that Fromm has also been run over. They want Wolfe to return the money, but Wolfe plans to use it to find her murderer.Archie talks to Lon Cohen to review Fromm's last day. After Wolfe hears the report, he sends Archie to see Jean Estey. While they talk, Paul Cuffner comes in and throws Archie out, and he returns to the brownstone. Saul, Fred, and Orrie are there and he sends them out on assignments.Archie returns to Jean Estey. He pretends to be corrupt and asks her for $5,000 in return for hearing Wolfe's conversation with Laura Fromm. She responds by throwing her drink in his face. He then goes to see Mrs. Horan with the same offer, but she also rebuffs him. Finally, he makes the offer to Angela Wright, the head of an immigration organization that Mrs. Fromm worked with, but she also turns him down. Archie returns to the brownstone where Paul Cuffner is in conference with Wolfe. Cuffner wants to pay the $5,000 to hear the conversation.Orrie finds the jeweler who sold the golden spiders. He says he sold the earrings to Laura Fromm. Saul goes undercover to the immigration organization, where Angela Wright refers him to Denis Horan. Later, he is visited by a thug, who demands $10,000 to get him false papers. Saul follows him to a restaurant. Orrie joins Saul while Archie goes to Fred who is also undercover, meeting men about Birch. Fred is taken for a drive and Archie follows. Archie slips into a building where Fred has just been searched and his gun taken. Saul also comes in as they are about to work Fred over. After a short firefight the thugs are tied up, and they find proof of the immigrant blackmail schemes. Under torture, the thug reveals a password they used to get tips and that Birch had been the head of the organization. Horan also comes in, obviously familiar with the operation. After discussing the situation with Wolfe, they take the three to the brownstone.The next morning, Cramer comes in. As they talk, Horan asks to speak to Wolfe. In Cramer's presence, he explains that Mrs. Fromm had told him there were blackmailers in the organization, and that he wouldn't represent Egan. Egan is brought in, and in turn fingers Horan as the culprit.The whole cast of characters is brought to the brownstone, including a trio of policewomen in plainclothes.
Wolfe reveals that the driver of the car who killed Pete Drossos was a woman, who had later overpowered Birch and killed him as well. He brings in a clothier who can identify a woman who had bought a man's suit recently. He identifies the killer.Later, Wolfe turns over $5,000 to Pete Drossos' mother, as he and Wolfe had arranged to be partners in the case.

Question: What did the undercover cops find on the thugs?
Answer: Proof of the immigrant blackmail schemes