DENVER -- A man who was accused of using other people's investment money for his own gain pleaded guilty to racketeering Monday.

According to the Denver District Attorney's Office, Mark Jackson, 55, pleaded guilty to violating the Colorado Organized Crime Control Act. Jackson was accused of taking millions from investors, with the promise of 12 to 36 percent returns, as far back as 1995. The district attorney's office accused Jackson of using that investment money to pay other investors, and also for his own benefit.

Jackson faces anywhere from probation to 20 years in prison. He'll be sentenced May 25.

According to state law, the Colorado Organized Crime Control Act makes it illegal to do the following:

1. It is unlawful for any person who knowingly has received any proceeds derived, directly or indirectly, from a pattern of racketeering activity or through the collection of an unlawful debt to use or invest, whether directly or indirectly, any part of such proceeds or the proceeds derived from the investment or use thereof in the acquisition of any title to, or any right, interest, or equity in, real property or in the establishment or operation of any enterprise.

A purchase of securities on the open market for purposes of investment, and without the intention of controlling or participating in the control of the issuer, or of assisting another to do so, shall not be unlawful under this subsection if the securities of the issuer held by the purchaser, the members of his immediate family, and his or their accomplices in any pattern of racketeering activity or the collection of an unlawful debt after such purchase do not amount in the aggregate to one percent of the outstanding securities of any one class and do not confer, either in law or in fact, the power to elect one or more directors of the issuer.

2. It is unlawful for any person, through a pattern of racketeering activity or through the collection of an unlawful debt, to knowingly acquire or maintain, directly or indirectly, any interest in or control of any enterprise or real property.

3. It is unlawful for any person employed by, or associated with, any enterprise to knowingly conduct or participate, directly or indirectly, in such enterprise through a pattern of racketeering activity or the collection of an unlawful debt.