Source: MLB has a lot more witnesses than just Anthony Bosch for its investigation against A-Rod, others

Major League Baseball's investigation into Alex Rodriguez and other players is being built on testimony and evidence provided by many witnesses in addition to the cooperation of the anti-aging clinic's founder, Anthony Bosch, a source familiar with the probe said Thursday.

Rodriguez, who is at the Yankees' minor-league complex in Tampa, Fla., rehabbing from hip surgery, issued his first public comments since ESPN reported on Tuesday that he could face a 100-game suspension for allegedly receiving performance-enhancing drugs from Bosch's now-shuttered Miami clinic, Biogenesis. The report said Bosch has agreed to cooperate with the investigation.

"Myself and others are being mentioned in a media report before the process is even concluded," Rodriguez said in a statement. "I would hope this thing would follow the guidelines of our Basic Agreement. I will monitor the situation and comment when appropriate.

"As I have said previously, I am working out every day to get back on the field and help the Yankees win a championship. I am down here [in Tampa] doing my job and working hard and will continue to do so until I'm back playing."

Commissioner Bud Selig declined to comment on the investigation and Rodriguez's statement while meeting with reporters at the MLB draft Thursday night.

"We're in the midst of a very comprehensive investigation and it would be inappropriate for me to comment," Selig said.

According to the source, interviews with "tons" of people will help frame the basis of MLB's investigation. Rodriguez is among those scheduled to be interviewed by MLB as part of the next phase of the investigation.

Rodriguez, who previously denied any wrongdoing, and Ryan Braun of the Brewers are among the biggest names who initially were reported to be linked to Bosch's clinic in a February story by the Miami New Times.

Bosch, in dated entries detailed by the Miami New Times, was reported to have allegedly sold and injected Rodriguez with illegal substances. In a late April interview with ESPN, Bosch said he would not discuss his baseball "clients," a reference seized on by MLB in establishing Bosch's link to players.

What the players say to MLB investigators could determine what, if any, discipline they may face.

According to the source, if players are found to have lied to investigators, that could result in a more significant penalty.

It appears that much of MLB's case will rest on what is called a non-analytical positive, meaning evidence other than a blood or urine test to detect banned substances.

The source said that while a positive test would be beneficial to investigators, the lack of a test would not necessarily clear a player.

Canadian arbitrator Richard McLaren, who assisted in the drafting of baseball's 2007 Mitchell Report on steroids and other PEDs, believes MLB will have a strong case.

"Yes, the whole scheme is designed around a positive chemistry analysis from a lab. However, the rules also say use or attempt to use, or possession, or attempting to possess an illegal substance," McLaren said. "Those are the two areas where you can get into a non-analytical positive. You don't have the lab result, it's a non-analytical positive."

McLaren said if penalties are levied, MLB will have to be prepared for arbitration hearings.

"You want to have as much corroborative evidence as you can find," he said. "So to the extent that there were employees, receptionists or whatever at the clinic who might have knowledge of what's going on, then you want them to testify, verify, corroborate someone else's testimony, like Bosch.

"So they would certainly be looking to obtain that type of information, and I would suspect they have some of that kind of information available to them and are prepared to call that at arbitration."

Derek Jeter, who also is in Tampa as he recovers from a broken ankle, said he spoke with Rodriguez, who seemed "fine."

"You guys know what I'm going to say: I do not comment on anyone's situation until they comment on it first," Jeter told a handful of reporters outside the complex. "So let him speak about it first."

Also rehabbing in Tampa is catcher Francisco Cervelli, who reportedly also could face suspension for his alleged ties to Biogenesis. "I got nothing," Cervelli said from his car window as he exited the facility.

With David Lennon

and Joey Knight in Tampa