Was it a publicly traded partnership (PTP)?  Held in a brokerage account?  Was everything else in the brokerage account transferred to the widow or otherwise administered?  

Half the K-1s I see are for units held in an IRA -- are you sure it has his name and SSN, or is it under an IRA in his name, and the trustee's EIN?  And some inherited IRA's still have the name of the decedent on the top line.