Conn. Gen. Stat. § 53a-54c

A person is guilty of murder when, acting either alone or with one or more persons, such person commits or attempts to commit robbery, home invasion, burglary, kidnapping, sexual assault in the first degree, aggravated sexual assault in the first degree, sexual assault in the third degree, sexual assault in the third degree with a firearm, escape in the first degree, or escape in the second degree and, in the course of and in furtherance of such crime or of flight therefrom, such person, or another participant, if any, causes the death of a person other than one of the participants, except that in any prosecution under this section, in which the defendant was not the only participant in the underlying crime, it shall be an affirmative defense that the defendant: (1) Did not commit the homicidal act or in any way solicit, request, command, importune, cause or aid the commission thereof; and (2) was not armed with a deadly weapon, or any dangerous instrument; and (3) had no reasonable ground to believe that any other participant was armed with such a weapon or instrument; and (4) had no reasonable ground to believe that any other participant intended to engage in conduct likely to result in death or serious physical injury.