What does George Santos' ex-campaign treasurer Nancy Marks' guilty plea mean for his criminal defense?

The Justice Department's announcement this week of a guilty plea from the Long Island-based ex-campaign treasurer for Republican Rep. George Santos signaled that the federal fraud case against the congressman is strong, according to legal experts. 

Nancy Marks appears to have had intimate knowledge of the thousands of dollars that flowed into and out of Santos' campaign accounts, making her the focus of federal scrutiny.

Marks, who was a top financial official on Santos' congressional campaign, pleaded guilty on Thursday to one count of conspiracy to commit offenses against the United States, which included wire fraud, falsifying records and identity theft, according to court documents.