If they can compare one of the weights brought up from the bay with one at Snott's house they can prove he was responsible. One could split the concrete and compare the minerology of each or they could compare the size coarse aggregate (rock part of the concrete) of each that was used (crushed or round river rock) to prove a match...as long as they have a sample from each it could prove decisive.....(I used to be in the business till Clintoon regime illegally shut me down- hence the name (this is where the plot thickens !)
Apprently they have just such an expert slated to testify!! He's toast!!