Not being a Colorado lawyer, I really do not know how
one goes about calling a grand jury in that state.
In most states, and in the federal system, grand
juries are convened by the court, either as a matter of regular practice
(since there are always some grand juries in session in states that
require their use to return indictments) or as a special practice, often
at the request of a prosecutor. In some states, there are special or
multi-county grand juries that are called into session to investigate
particular matters. If you want to find out more about those, and about
whether Colorado has them, you could download the law review article you
can access via one of the red buttons on the first page of the site (or
print it out) - it surveys grand jury practice in the states, and covers
Another thing you could do is go to FindLaw (www.findlaw.com)
and check the Colorado statutes and court rules governing grand juries.
You can find them in the "states" part of FindLaw. Check for both
statutes and court rules, since both usually govern grand jury practice.
They should tell you how a grand jury is convened in Colorado.