Coworker's embezzlement and his wife

My boss and I found out that one of our coworkers withdrew almost all the money that was in the bank accounts under his name but was the fund for our company's project.

As we were investigating his act and the relations of other people in this matter, his wife claimed she kept the passbooks with her in a safe for a few weeks because she knew that her husband was misusing our company's money and wanted to prevent more crimes committed by her husband. However, the husband still could withdraw money since he is the signatory who can process transactions without the presence of the passbooks. Now we are taking legal action against him to get the money back, but are also wondering if we can make his wife responsible and a joint guarantor, since she caused the delay in the disclosure of this issue by not reporting to us about her husband's misuse while keeping the passbooks. Can we ask his wife to cooperate in returning the money that my coworker stole from our company? Thank you.