Young's family was more than $40,000 in debt when he traveled to Washington in the summer of 2008 to confront Edwards about the Hunter affair, Walsh said.
Walsh also testified that Baron wired Hunter $74,000 over six months in 2008, well after Edwards dropped out of the presidential race. Baron started giving Hunter money in June and made eight payments to Hunter, most of them for $9,000.
For its first witness Monday, the defense called Lora Haggard, who worked as the chief financial officer for Edwards' 2008 presidential campaign.
She testified Edwards had nothing to do with reports the campaign filed with the Federal Election Commission.
"Mr. Edwards was not involved in the review, preparation or filing of the reports," she said. "We rarely saw him in (campaign) headquarters" in Chapel Hill, North Carolina.
Haggard's testimony is important, as Edwards is accused of making false statements because he never disclosed donations from Baron and Mellon.
Haggard also testified that she thought the checks from the two donors did not belong on FEC forms because they were personal gifts, not campaign contributions. Finally, she said the FEC knew about the checks from Baron and Mellon because the campaign was still undergoing an FEC audit at the time of Edwards' indictment.
Prosecutors wrapped their case last week, detailing hundreds of thousands of dollars in expenses used by Edwards' former mistress.
If convicted on all counts, Edwards could face up to 30 years behind bars.