If he sues and goes before a judge and tells the judge he and his agent were "told" it was signed and accepted but you can't produce a document, it will get thrown out without hesitation.Even with the agent as a witness (the agent the seller told it was signed and accepted), without an actual document, no judge would rule in favor. 

If you take it to closing the Title Company Agent can witness it.  

I graduated from college with a business degree wit Real Estate as an emphasis and I got a broker license in 1980.  

@Douglas Skipworth  I thought so most states you have to be licensed.So how can a company like mid south if those complaints on BB are true still be in business if indeed they still are.I know in CA and MS and OR were I have brokers license's these violations would be dealt with swiftly and licenses would be revoked in almost all cases unless it was a small violation that got correct.. but having witnessed first hand what goes on in the mid west and deep south in the rental game I would pro offer that this behavior if true is prevalent in the organization in question.AS for getting the word out on a PM review site that will be easy...

I have found a property which I am meeting with the seller to sign the contract, but this will not be my typical contract signing as it will be my brother signing to purchase wit ha FHA 203K loan.  

Thanks @Jerry W., its always nice to have a professional opinion.

@Barbara Chan, @Nicole W."It

The camaraderie that I've witnessed between real estate investors is intense, like a big group of people that are taking back their time through investing and sharing.  

Have the tenant sign the estoppel (with a witness) to attest to its content.If there is a discrepancy between the amount of rent identified by the Vendor and what the Tenant claims to be paying - or any other difference between the lease and estoppel  - make it the Vendor's responsibility to explain or rectify the situation.You will inherit the existing lease and will be obligated to honour its conditions.  

Keep the property (no, owner wants nothing to do w/ it), b.