Hi Abby, welcome to the board. Yeah, honestly, she wouldn't be able to tell that. In the episode they determine it to be slate, so I would have thought that the obvious choice would have been that it was from a roof tile, but that's just me. Because I'm in the mood for looking things up, I had a look back at the episode and at one point Stella says something along the lines of the cuts made on the victims being from a gravestone or 'something made of the same kind of material', so she's keeping an open mind. And later when they are identifying the trace elements found in the lacerations, the computer screen says that it's 'hypothetical origin' is a gravestone. So basically Lindsay was guessing at the origin, and was correct of course due to it being necessary for the plot. :lol:[/quote] OK, I guess I can accept that. I know that we have to suspend disbelief, but that just seemed like such a fantastical leap. I admit that Lindsey drives me up the wall so I tend to tune out everything she says. Which makes following some of the plot line difficult! :lol: I just have to thank my lucky stars that she didn't do some goofy "imitating a gravestone" demonstration like she did climbing into the trunk. I can't believe that Mac accepts that kind of nonsense from her.