Gardner pleaded guilty last month to Amber's murder and also to the rape and murder of Poway teenager Chelsea King.
Carrie McGonigle wants answers about her daughter's last moments.
"I need the answers for closure," McGonigle said.
The only man who can provide those answers has publicly said he will answer Mcgonigle's questions. So far, though, her efforts to arrange a meeting at the county jail have been rebuffed.
"[At] 4:30 on Friday, I was informed I was put on a 'no visit' list by law enforcement, and I wouldn't be able to go visit," McGonigle said.
McGonigle asked Gardner's attorney Michael Popkins for answers, and, via e-mail, he told her: "Mr. Gardner has expressed a willingness to speak to both families privately and answer any questions you may have.... Please respect that I must do my job and not allow Mr. Gardner to speak to anyone prior to sentencing."
Other lawyers, however, said Monday that Gardner's attorney can only "recommend" that Gardner not meet with visitors and that he has no control over his client.
"The client still has free will," attorney Gerald Blank said. "It's the client's final decision as to with whom the client wishes to speak. That's the client's decision, not the lawyer's decision."
The sheriff's department, which runs the jail, confirms that if McGonigle wants to talk with Gardner during visiting hours, he is allowed to meet her.
"You know, it's been 15 months -- 15 months and one day at sentencing, and we don't have answers," said a weeping McGonigle. "For me, that's the type of person I am, I need answers."
Gardner's lawyer declined to comment on the issue. Amber's father, Moe Dubois, and Chelsea King's parents, have said they have no interest in talking privately with Gardner.