As Jeff Conaway struggles to hold onto life, his former Taxi co-stars Tony Danzaand Marliu Henner have maintained a bedside vigil of their beloved friend since he was hospitalized, RadarOnline.com has exclusively learned.

"Marilu has been talking to Jeff, and he seemed to be trying to respond to her over the weekend, even though he has been in a medically-induced coma," a source close to Conaway told RadarOnline.com.

PHOTOS: Stars Who OD'd

"Jeff would turn his head towards Marilu when she was talking to him. It was truly a touching moment," added the source.

Despite initial reports that Conaway, who was found unconscious on the floor of his Encino home May 11, had intentionally overdosed on prescription drugs, our source reveals, "there is no evidence that Jeff intentionally took an overdose of pills, period. Jeff likely aspirated one of the pills into his lungs, prompting the pneumonia that he is now suffering from.

Read the full story at RadarOnline.com.