Beth Twitty met with him Saturday and urged him to pressure the island's authorities to do more to find her daughter.
The Alabama teen vanished on the island almost three months ago on a high school graduation trip. Wednesday would have been her first day at the University of Alabama.
Speaking to co-anchor Hannah Storm on The Early Show Monday, Twitty said there still aren't any answers about Natalee's fate, and her meeting with the prime minister reinforced some views she has.
"We've lived on this island now for three months," Twitty says, "and I see just how small it is, and I see just how connected it is, and everyone knows everyone in Aruba. This shouldn't be a mystery in Aruba. And I know the answers are right here.
"I don't think that we can even say it's only limited to these four men that have the answers, the Kalpoe brothers and Joran and Paul van der Sloot. There are more people involved in this (who) know what happened.
"I'm just really reaching out to (the prime minister) to make this happen and whoever he needs to put the pressure on, even if it's on the defense team, the prosecuting attorney, I mean, something needs to happen."
Joran van der Sloot is the only suspect still being held in the case. His father, Paul van der Sloot, was briefly detained, as were the two Kalpoe brothers, thought to be the last people seen with Holloway, along with Joran van der Sloot, the night she disappeared.
Under Dutch law, Joran could be released as soon as Sept. 4, which concerns Twitty: "We are so in the dark during most of this investigation, we cannot put any faith in it that he will be held, that they have all this evidence that is mounting against Joran. I think it's anybody's guess (whether he'll be kept behind bars). I'm thinking the one thing coming up — I know elections are coming up Sept. 23. I have a feeling they're going to feel the pressure to keep him in for at least another 30 days. But I just don't know."
Twitty says the start of school has added to the family's suffering.
Not only was Natalee due to start college this week, her close friends have been scattering to do the same, and Twitty's son, Matt, is already back in class.
What's more, "I'm also to be back at my job. I've been a speech pathologist for 22 years in the public school system. This is the first time that I've not been able to return to my job. All of our lives have just been ripped out from under us."