DALLAS — The National Football League and its union, which had two players involved in three violent deaths in a week, may face increased pressure to improve how they help players with mental-health and substance-abuse issues because of fan expectations.

"It's critical that the league and the union get in front of these issues in a very public way," Paul Swangard, managing director of the Warsaw Sports Marketing Center at the University of Oregon, said in an email. "Fans will want to know: 'What are you doing about this?'"

Cowboys defensive tackle Josh Brent was charged with intoxication manslaughter following a car crash over the weekend that killed his teammate and friend Jerry Brown. A week earlier, Kansas City Chiefs linebacker Jovan Belcher shot and killed his girlfriend before killing himself with a gunshot to his head outside Arrowhead Stadium.

The deaths have rocked the nation's most popular sport at a time when television ratings for NFL games are at an all-time high and league revenue has surged to about $9.3 billion.

The NFL and its 32 teams, along with law-enforcement officials and counselors, educate rookies at an annual symposium and at other times of the year on issues including guns, alcohol, prescription drugs and other substance abuse, league spokesman Brian McCarthy said in an e-mail.

"We also emphasize personal responsibility and decision- making," McCarthy said.

Before Sunday's game against the Bengals at Paul Brown Stadium in Cincinnati, Cowboys players bowed their heads and some covered their hearts during a moment of silence. The Cowboys won 20-19.

"Our team is grieving," Dallas owner Jerry Jones said in an interview on Fox television. "There's something more important than football and this is life, and certainly the lost life of Jerry."

Brent, 24, was driving at a high speed when the vehicle hit a curb in the Dallas suburb of Irving, and flipped at least once, according to police. Brown, 25, was taken to the hospital, where he died, Argumaniz said.

"I will live with this horrific and tragic loss every day for the rest of my life," Brent said in a statement released by his agent, Peter Schaffer.

The NFL Players' Association reiterated that it has a 24- hour car service available to all its members.

"That service does get utilized regularly," George Atallah, a spokesman for the union, said in an email. "That phone number is on the back of every player's union card."

In addition, the league labor deal struck a year ago includes programs to help players with substance abuse along with a 24-hour counseling service for those with mental health concerns, Atallah said.

The union has resisted attempts by the NFL to suspend players for two games who are found guilty of a first drunken driving offense, NBC Sports said on its website. The penalty currently is the loss of two game checks, the report said. An agreement reached last year to impose a one-game ban and a one- game fine has yet to be implemented, NBC said.

"I'd be very surprised if the union agreed to more stringent sanctions," Rick Burton, a professor of sports management at Syracuse University's Falk College of Sport, said in a phone interview.

Champaign County, Ill., Court records show Brent was sentenced to 60 days in jail, two years of probation, 200 hours of community service and a fine of about $2,000 for driving under the influence, speeding and driving without a valid license in February 2009 near the University of Illinois, where he attended college, the Dallas Morning News reported.

"There should be an automatic two-game suspension on the first DUI," said CBS Sports analyst Bill Cowher, who guided the Steelers to victory in the Super Bowl after the 2005 season. "That's the only way to get the message through. The only hammer you have is playing time. Fines won't get it done."

NFL Commissioner Roger Goodell will probably face pressure to investigate whether collisions that cause concussions were a factor in Belcher's actions, Burton and Rosner said.

"I don't know if there's a correlation, but that may be the perception and the NFL should be seen to be examining the possibility," Burton said.

The tragedies of the past week are unlikely to affect the league's business over the long term, said Steve Rosner, co- founder and a partner in East Rutherford, N.J.-based 16W Marketing.

"It's a black eye on the individuals rather than the league," Rosner, whose clients include baseball's Cal Ripken Jr., basketball's Hakeem Olajuwon and football's Howie Long, each retired and a member of his sport's Hall of Fame, said in a telephone interview. "The NFL is on a very high pedestal and it would take a lot to knock it down."

The sport is almost immune to negative publicity, Stephen McDaniel, who teaches sports and entertainment marketing at the University of Maryland, said in an email.

Television ratings and league revenue are at record levels even after a lockout and scandals involving some its highest- profile players in recent years.

Quarterback Michael Vick's conviction for dog-fighting; wide receiver Plaxico Burress's incarceration on a weapons charge; Pittsburgh quarterback Ben Roethlisberger's four-game suspension after being accused but not charged with assaulting two women; a 162-day player lockout, criticism over the use of replacement referees; or a bounty scandal involving the New Orleans Saints in which the NFL said players received money for hits that injured opponents.

Even increased penalties won't be enough to eradicate the risk of further incidents like the two in the past week, Rosner said.

"The NFL is being as aggressive as it can to police their players," Rosner said. "But sometimes individuals do things that can't be legislated for, no matter how scrupulous the league is."