If not the Borrower's credit report and payment history are the best sources for info.

@Nick PowellI would first suggest trying to get a loan from a different source.

Where is the money coming from now that their employment is gone which was the only source of income to pay for a home? 

@Allison Winston - If you're able to source good deals, consider bringing on a partner to help with the funding.

And then the lockdown happened.My question is - what is the source of truth?

The value to the buyer can add up to a very sizeable amount of money; typically pays the up-front lender fee to lower the interest rate, which results in accumulating paid interest savings for the buyer as long as the buyer owns the property, or for the life of the loan; may add up to many tens of thousands of dollars; make sure you check the fine print of the lender's loan lock provisions; be sure your seller's money is truly paying down the loan rate as opposed to paying other lender charges to the buyer.  3.Seller-Funded Temporary BuydownsBuydowns can also be structured to adjust the buyer-paid interest rate for a limited number of years; can cover the first two, three or four years or more of the buyer's loan; allows your seller to reduce the buyer's ongoing loan cost (monthly payment) considerably.4.Owner FinancingA willing seller may be able to keep their selling price intact by offering financing to a buyer; for a seller who needs to sell as soon as possible for the best possible price; expands the potential market for buyers to those who might not qualify with a lender for any number of reasons relating to their credit, verifiable income, or other issues; seller creates an 'investment" that can produce an annuity with a very good rate of return for many years; seller needs to become very well educated on how to qualify a potential buyer (how to get credit, income, debt ratio, and other accurate personal historical data on the buyer-and how to verify that data); seller needs legal advice to review contract documents, as well as title and escrow services to conduct a title search and closing; buyers attracted to seller financing may have income sources including part- time work, bonus income, royalty income, dividend and interest income from investments, or they may be newly self employed; seller who finances needs to get a substantial down payment and ensure that the property is adequately insured by the buyer and that initial property taxes are pre-paid and a tax payment plan is established; if the buyer stops paying, the seller will have to proceed like a bank or other lender and foreclose on the buyer. 5.Contract for DeedA contract for deed agreement to purchase is similar to a seller-financed purchase.

Always trust your source and make sure the ARV is as accurate as you can get it up front. 

FYI - I am a foreign national and I don’t leave there, so I can’t go with him.

It’s my opinion that unless you intend to take up brokerage as an additional source of income, it’s not a good idea.

HELOC is a good source of cheap money, if your are willing to risk your house in the event the deal you do goes bad, usually reserved for an experience investor.