Bumping this up with a comment about Jimmy Hydell being given a contract to whack Casso....

In my opinion, the attempted murder of Casso seems to have been in retaliation for Gaspipe blowing up Frank Decicco, and his plans to whack John Gotti. Angelo Ruggiero gave the contract, and he was close to Gotti. However, most accounts don't link the attempt on Casso's life with his focus on whacking Gotti, nor with DeCicco's murder.

The popular theory seems to be that Angelo acted alone and without Gotti's knowledge. I find that very hard to believe. Both the DeCicco murder and the attempt on Gaspipe's life occurred in 1986, so the timeline works.

I really enjoyed this book and recommend it.