Concerned that some players might be flashing the hand signals of street gangs, the NFL has hired experts to examine game tapes to look for gestures, the Los Angeles Times reported.

Mike Ahlerich, the NFL's vice president of security, told the Times "there have been some suspected things we've seen."

Ahlerich told the newspaper that the NFL has warned its players about the influence of gangs and organized crime. He added that the league has stepped up its reminders since Denver Broncos cornerback Darrent Williams was gunned down in 2007.

Athletes flashing signs was brought to the forefront in April when the Celtics' Paul Pierce was fined for making "menacing gestures" to the Atlanta Hawks.

Mike Pereira, the NFL's vice president of officiating, told the Times that the league was always suspicious of gang-related hand signals happening during games, but that the Pierce incident "brought it to light."

According to the Times, the league decided to make the identification of gang signs a point of emphasis this season.

The newspaper reported that NFL officials will not be responsible for identifying gang signals, but that they will alert the league headquarters if they see anything suspicious.