By Thomas Frank, USA TODAY

Authorities at Super Bowl XLIII will be looking for more than just drunken fans. They'll be watching spectators' body language, facial expressions and demeanor to find suspicious people.

For the first time Sunday, federal behavior-detection officers will team with local police to use a controversial technique on people heading to a major event, the Transportation Security Administration (TSA) says. The officers usually work in airports.

Behavior observation aims to find people in crowds acting unusually. A flagged person gets a casual interview from an officer who determines if he or she should be formally questioned or arrested.

At the Tampa Police request, the TSA is sending dozens of its behavior officers to Tampa to watch spectators entering 75,000-seat Raymond James Stadium on Sunday, said Tampa Police spokeswoman Laura McElroy. The TSA on Jan. 13 gave a four-hour training overview on behavior detection to 100 Tampa-area police, TSA operations chief Lee Kair said.

"They'll be a dedicated set of eyes looking for suspicious behavior," McElroy said of TSA officers.

"Police shouldn't be stopping and questioning people unless they have some credible reason to suspect them. Behavior detection is just too vague," ACLU analyst Barry Steinhardt said. He noted sarcastically, "If we're going to use this at high-profile sporting events, why not start using it on streets?"

Behavior observation is used daily by 2,600 specially trained TSA officers at more than 160 airports. Officers look for obvious signs of nervousness or other behavioral flags, such as sweating, avoiding eye contact or talking evasively.

Police want to guard against an attacker such as the man who drove to last year's Super Bowl site near Phoenix with an automatic rifle intending to open fire, McElroy said. The man, Kurt William Havelock, apparently changed his mind in the stadium parking lot and turned himself in. He was sentenced in October to a year in prison for making threats.

The TSA officers, who get seven days of training, will take the lead in spotting suspicious spectators, while their police partners will do the questioning, McElroy said. Police around the USA are asking for the TSA training, Kair said.