Exchanges are complex, and i agree you should consult  a local tax person because you have an unusual situation, but make sure the person is very knowledgeable about 1031 exchanges. 

Until you have an answer to completing the exchange there are some things you need to know, in case you don't already know. In an exchange, an intermediary is brought in at the time of the original property sale.  That intermediary takes charge of the funds from the sale because those are the exact same funds that must be used in the purchase of the replacement property.  (Not just the same amount of money but that exact same money). 

The seller must also file a form within 45 days, identifying the possible replacement property.  It's possible your brother did engage such an intermediary, who may be holding those funds and it's very important that they not be intermingled with any other funds, such as general estate funds.  His real estate broker would be the place to ask whether your brother had taken the necessary steps to begin to execute an exchange.