Both of the above writeups are excellent, though I do have a bit to add. The segment (which, incidentally, was one of my absolute favorite programs ever) was particularly memorable for its dramatic intro spiel, a loose take-off of Dragnet. Of course, seeing Monday and Friday whip calculators out of shoulder holsters was also quite memorable... The Mathnet theme, to the tune of the 'Dragnet' theme, is:

The story you are about to see is a fib - but it's short.
The names are made up, but the problems are real.
Mathnet, the documented drama of an actual crime.
For the next 60 minutes, in cooperation with CTW,
you will travel step-by-step on the side of the law through an actual case, from beginning to end.
From crime to punishment, Mathnet is the story of your mathematicians in action.