Case study question forensic accounting

A man was on remand in prison having been charged with drug dealing. No drugs were ever found and the evidence against him was simply that he owned a number of properties but worked as a cleaner in a localfactory. The implication was that the property purchases could only have been funded from the proceeds of crime. The man denied this. A forensic expert was instructed to review the man’s financial affairs and explain how the man funded his lifestyle. 
The expert made a detailed review of the man and his family’s financial affairs, starting at the time he bought his first property. The records explained the sources of all the funds used to buy the properties. It showed how the man had used equity created through the legitimate purchase and sale of other properties to create his portfolio and support his family’s lifestyle. The court accepted this fraud investigation report in its entirety and the man was released from remand without charge.
i. What type of evidence do you think the expert would have gathered for his report?ii. Which documents could have helped the forensic expert in gathering evidence?