Deepak Kalpoe (search ) filed a complaint against Natalee Holloway's (search ) mother Tuesday, claiming he felt he was threatened by her actions at his place of work, Fox News has confirmed.

Beth Holloway Twitty (search) confronted him Monday at the Internet cafe where he works, spending about 90 minutes peppering him with questions.

Kalpoe's lawyer has sent her a letter warning that if she does it again, he will file for a restraining order against her.

Brothers Satish and Deepak Kalpoe, and 18-year-old Joran van der Sloot (search ) were among the last people to see Holloway, 18, of Mountain Brook, Ala., before she vanished on the final night of a high school graduation trip to Aruba.

Holloway Twitty said Monday the investigation into the teen's two-month disappearance has been marred by ineptitude, and more than doubled the reward for help in solving the case to $250,000.

Renewing criticism of authorities on the Dutch Caribbean island, Holloway Twitty said police had given her copies of statements from witnesses and other documents from the investigation that have led her to believe investigators are on the wrong track.

"The level of ineptness has been incredible," Holloway Twitty said of Aruban authorities. "The whole thing has been wrong from the beginning."

She declined to give details on the documents or say how she thinks authorities should be handling the case.

The family is also offering a $1 million reward for information leading to the 18-year-old's safe return. The other reward was raised from $100,000, and Holloway Twitty wanted to publicize the rewards in neighboring Venezuela and Colombia, even though Aruban authorities and the FBI said they don't believe the teen left the Dutch Caribbean island.

The family has said the reward is a mix of their own money and donations, but they have declined to give a breakdown.

"I hope more money will help bring people forward," she said in an interview with The Associated Press. "I still don't feel like this investigation is heading in the right direction."

Chief Prosecutor Karin Janssen called the criticism unwarranted.

"I'm positive about our progress and very proud of my team," said Janssen.

Extensive searches by Dutch marines, Aruban police, and thousands of volunteers have found no trace of Natalee, who vanished on May 30 during a graduation trip with 124 classmates on the island.

No one has been charged in the disappearance. Seven men were arrested, including Satish and Deepak Kalpoe, but all except van der Sloot have been released.

Through his lawyers and family, van der Sloot has acknowledged being on a beach alone with the young woman the day she disappeared, but says he left her there unharmed.

The Associated Press contributed to this report.