Federal agents turned off Internet access to three luxury villas at a Las Vegas hotel then impersonated repair technicians to surreptitiously get inside and collect evidence in an investigation of online sports betting, according to defense lawyers challenging the practice.

The FBI employed the ruse against the recommendation of an assistant U.S. attorney, Kimberly Frayn, according to lawyers for four of eight men charged in the case. They filed a motion late Tuesday in federal court in Las Vegas to dismiss evidence in the case. According to a conversation recorded by an investigator for the hotel, the prosecutor told FBI agents "it was a consent issue," the lawyers said.

Under U.S. law, a person whose property is inspected generally must waive his constitutional protections against unreasonable searches unless authorities obtain a warrant. Evidence collected improperly is not supposed to be used at trial.

The FBI in Las Vegas referred questions about the practice to the U.S. Attorney's Office there. Natalie Collins, a spokeswoman for U.S. Attorney Daniel Bogden, said prosecutors were aware of the allegations being made by defense lawyers but declined to comment, citing a pending trial.

The case was at least the third to surface in recent weeks raising questions about tactics by federal agents pursuing criminal investigations. The Drug Enforcement Administration set up a fake Facebook account using photographs and other personal information it took from the cellphone of a New York woman arrested in a cocaine case in hopes of tricking her friends and associates into revealing incriminating drug secrets. In another case, the FBI sent a fake news story it attributed to The Associated Press to trick a suspect in a bomb-threat case into clicking on the website link and revealing his location. The AP on Tuesday objected that the FBI's practice was "unacceptable" and "undermined AP's credibility."

According to the criminal complaint in the gambling case, the eight men came to the attention of authorities in late June after they requested "an unusually large amount of electronics equipment and technical support." An electrical engineer employee advised security personnel at the hotel that the equipment in one of the villas "appeared to be set up for an illegal gambling operation."

Over two days in early July, FBI agents worked with a hotel computer contractor and the state's gaming control board to shut off the Internet at different times and at one point delivered a laptop computer to try to see what was happening, according to the court filing. Investigators eventually gained access after they turned off the Internet connection to two suites, impersonated repair technicians and recorded video inside. Authorities later used the videos to obtain a warrant to arrest the men.

In the criminal complaint, federal agents said the videos showed evidence of an illegal online sports gambling operation being run out of the villas. Prosecutors did not mention in the criminal complaint what caused the Internet outages.

Defense lawyer Thomas Goldstein said lawyers learned about the ruse only when they reviewed the video recordings and heard an official make reference to turning off the Internet access.

"They were trying everything they could to get inside without a warrant," Goldstein told the AP.

A former federal prosecutor, Mark Rasch, said the ploy probably will not stand up in court.

"Police are allowed to use a certain kind of subterfuge, but what they can't do is create a certain kind of circumstance," Rasch said.

In the gambling case, Wei Seng Phua, his son Darren Wai Kit Phua, Seng Chen Yong and Wai Kin Yong and four others were arrested in July after federal agents raided the three high-roller villas at the hotel.

All eight face charges of transmission of wagering information, operating an illegal gambling business, and aiding and abetting. None of defendants has entered a plea, but Goldstein said Tuesday they all deny wrongdoing.

Wei Seng Phua, 50, also faces charges of running an illegal sports gambling business in Macau. He was arrested in the Chinese gambling enclave on June 18 and flew to Las Vegas a few days later.

In a criminal complaint, federal authorities described him as a high-ranking member of the 14k Triad, a Chinese organized crime group.

Goldstein said Wei Seng Phua also denied that allegation, which he said had nothing to do with the criminal case in Nevada.