Risa

Yeah, the official story is that Locarno was too fucked up for audiences to forgive. Jeri Taylor said:

"We had liked the idea of a character like Tom Paris ever since we had done "First Duty" and had Lecarno [sic.]. We didn't make Lecarno the con officer, because he was somewhat darker and more damaged. We felt Lecarno couldn't be redeemed and we wanted to be on a journey of redemption."

Personally, I think Locarno would have been a great choice, because while I like Tom Paris just fine, Voyager utterly failed at selling the idea that he was in need of redemption or a "bad boy" of any kind.