How to change search results to show full posts instead of excerpts?

Hi, folks:

How can I change search results to show full posts instead of excerpts that currently display? Ideally, I would like an option in the search form to specify returning a list of excerpts or a list of entire posts.

Running Atahualpa 3.4.6 under WP 2.9.2. I examined wp-content/default/search.php, but can not find code specifying the_excerpt(). So I suspect Atahualpa may be handling the search?

Thanks for your help,

Fred