Robert Carradine Went MIA From Final Film Project, Director Says

The death of Robert Carradine has shocked Hollywood ... but TMZ has learned there was a troubling sign on his final film project, according to one of his most recent colleagues.

Connie Lamothe, director of "The Driver" -- AKA "Driving into Darkness" -- tells TMZ … she's shocked and devastated about "Bobby's" death … but she knew there was something wrong when he went MIA from her film prior to the table read this week.

Everything was finally back on track and moving along well after the project got derailed by the pandemic … but then in January, Connie tells us Robert went radio silent. Producers had no idea where he was or what was going on. They were worried ... but a friend who is also in the cast knew of his struggles with mental health. So, they decided to give him some space ... and hoped he would return.

As we reported ... the "Revenge of the Nerds" and "Lizzie McGuire" icon took his own life after a nearly two-decade-long battle with bipolar disorder.

Robert had been super excited for the project -- a crime drama in which he was playing a mob boss, a leading role -- Connie says, noting the actor wanted to show he could do more than comedy and westerns.

Recalling their time together during pre-production, Connie says Robert was delightful and always cheerful when they spoke -- including when she joked with him about cutting his hair and shaving off his beard for the role.

Robert was 71.

RIP