CHICO, Calif. (AP) – Jose Canseco wrote the book that helped persuade baseball to toughen its steroids policy, and he insists there’s much more damaging information to come.

“I think what we’re seeing is just the tip of the iceberg,” Canseco said Monday, about five hours before he took the field for the first time with the San Diego Surf Dawgs in the independent Golden Baseball League. “I know for a fact that’s what we’re seeing.”

Canseco received a smattering of boos and cheers before the game when he was announced as the designated hitter against the Chico Outlaws, then again when he stepped into the batter’s box leading off the second inning.

Canseco, who had said it had been at least four years since he last swung a wooden bat, struck out swinging on four pitches. He struck out swinging again in the third – this time on five pitches – getting razzed in the process.

“Juiced!” one fan hollered, a reference to his book. “That’s not a big league pitcher, Jose,” another man yelled.

Earlier, Canseco called Major League Baseball “the mafia” for the way it has handled the game’s steroids scandal and suggested that the sport will discipline only certain players and might even hide the truth when it comes to big-name stars and positive tests.

He plans to fight baseball to bring out the truth.

“They’re mafia, point blank, they’re mafia,” Canseco said. “I don’t think Major League Baseball is enthused about finding out the truth. There needs to be a major cleanup in Major League Baseball. I think they are treading on very thin ice, and (commissioner) Bud Selig has to be very careful what he’s doing because his job is on the line.”

When contacted about Canseco’s comments, baseball spokesman Pat Courtney said, “We wouldn’t comment on anything he said.”

One day after his 42nd birthday, Canseco showed up at the ballpark tanned and toned with his short, black hair slicked back. He sported tight jeans and a black button-down shirt, with several of those buttons open, exposing his muscular chest. And he noted that years of steroids use has helped slow the aging process for him. He weighs 230 pounds – down significantly from his playing weight of between 255 and 260.

Canseco carried a fancy, red duffel bag when he made his entrance into the modest, 4,100-seat ballpark on the campus of rural Chico State University, some 170 miles north of the San Francisco Bay area. A sellout crowd turned out for Canseco’s return.

The former slugger – he has 462 career home runs – was back in professional baseball for the first time since finishing his 17-year major league career with the Chicago White Sox in 2001. Canseco signed with the Surf Dawgs last week for the remaining two months of the season, set to earn the league’s maximum salary of $2,500 a month. He even plans to pitch, featuring a knuckleball, and threw a bullpen session before Monday’s game.

It is unclear when Canseco might take the mound for the first time.

Before the game, the Outlaws gathered in the shade and watched Canseco hit about six homers during batting practice. Even concession stand workers left their posts to take a peek.

He was initially slated to bat cleanup, but Kennedy later moved him down to sixth. Canseco pulled on a navy blue Surf Dawgs cap and held up his No. 33 uniform in a 20-minute outdoor news conference held in front of about 50 people, including a couple of fans wearing Oakland Athletics gear – his first club.

Canseco’s return comes some 16 months after he attracted Congress’ attention with an autobiography, “Juiced,” that accused several top players of steroid use – including fellow Cuban Rafael Palmeiro, who was suspended on Aug. 1 last season for violating baseball’s new steroids policy and claimed he didn’t know how the drug got in his body.

In March 2005, Canseco testified before the House Government Reform committee that he used performance-enhancing drugs as a player.

He also said Monday that New York Yankees star Alex Rodriguez told him after Dan Marino’s Pro-Am golf tournament about six years ago that Canseco was being “blackballed” by baseball.

“I challenge him in a polygraph test to say no,” Canseco said.

Canseco is working on a movie and two more books, saying he intends to “rectify” his tarnished image.

“The movie is going to be devastating, no ifs and buts about it,” he said.

Canseco said he will meet in the coming weeks with former Senate Majority Leader George Mitchell, appointed in March by Selig to head the sport’s investigation into steroids.

Baseball has toughened its drug policy several times in recent years, but Canseco isn’t satisfied.

“They now realize it started with me and ends with me,” he said. “The policy sounds great, but that’s not the problem. There are major problems not with the policies but the individuals who are instituting this policy.”

AP-ES-07-03-06 2255EDT