Preserving a dynamic webpage /static web page as an Evidence

there is a add-on for Mozilla Firefox called Scrapbook.

It will do exactly what you want to do in this scenario.

You can capture the entire webpage, with graphics, audio, video, flash, etc and it wraps everything into a nice time and date stamped folder.

You can then view the entire page offline at your convenience.

Another way to copy a site or perform similar page "rips" is to use HTTrack, a bit more complicated to use but once you learn the basics, it can be very useful.

HTH
/neo