What would it take for someone to purposely have an entry deleted from
the Google index. This page:
http://www.cs.toronto.edu/pub/path/u.can.15 was in the index last week
when I was investigating an individual mentioned on the page. He knows
he was being investigated. Today, this page no longer shows up in a
Google search. What would he have had to do to make that happen?

The official ways to do it are listed here:
://www.google.com/remove.html

The most likely answer is that the page just naturally fell out of the
Google index - a coincidence.

But that would require him to have access to the web site or know
someone who does in order to place the robot.txt files. That's not the
case here. Thanks, though :-)

Try the following link to get the old site info
 http://www.waybackmachine.org/

FarmerBob

You can still search on the page's contents via Hotbot, Wisenut, and
Yahoo; so this supports the proposal that it fell out of the Google
Index naturally.