Editor's note: The Associated Press has combed through the results of 2 1/4 years of investigations and uncovered some startling findings about the death of Pat Tillman, a football player who walked away from an NFL contract to serve in the U.S. Army Rangers. This is the second of three parts.

By SCOTT LINDLAW and MARTHA MENDOZA

The Associated Press

Had it happened in the United States, police would have quickly cordoned off the area with "crime scene" tape and determined whether a law had been broken.

Instead, the investigations into Pat Tillman's death have cascaded, one after another, for the past 30 months.

For Mary Tillman, getting to the bottom of her son's death is more than a personal quest.

"This isn't just about our son," she said. "It's about holding the military accountable. Finding out what happened to Pat is ultimately going to be important in finding out what happened to other soldiers."

In the days after the shootings, the first officer appointed to investigate, then-Capt. Richard Scott, interviewed all four shooters, their driver, and many others who were there. He concluded within a week that the gunmen demonstrated "gross negligence" and recommended further investigation.

"It could involve some Rangers that could be charged" with a crime, Scott told a superior later.

Then-Lt. Col. Jeffrey Bailey later assured Tillman's family that those responsible would be punished as harshly as possible.

But no one was ever court-martialed; staff lawyers advised senior Army commanders reviewing the incident that there was no legal basis for it.

Instead, the Army punished seven people; four soldiers received relatively minor punishments known as Article 15s under military law, with no court proceedings. These four ranged from written reprimands to expulsion from the Rangers. One, Sgt. Greg Baker, had his pay reduced and was effectively forced out of the Army. The other three soldiers received administrative reprimands.

Scott's report circulated briefly among a small corps of high-ranking officers.

Then it disappeared.

Some of Tillman's relatives think the Army buried the report because its findings were too explosive. Army officials refused to provide a copy to the AP, saying no materials related to the investigation could be released.

Not 'validated by facts'

The commander of Tillman's 75th Ranger Regiment, then-Col. James C. Nixon, wasn't satisfied with Scott's investigation, which he said focused too heavily on precombat inspections and procedures rather than on what had happened.

Scott "made some conclusions in the document that weren't validated by facts" as described by the participants, Nixon would tell later investigators.

Nixon assigned his top aide, Lt. Col. Ralph Kauzlarich, to lead what became the second investigation. Kauzlarich harshly criticized Baker and the men on his truck.

Among other things, Baker should have known that at least two of his subordinates had never been in a firefight, and should have closely supervised where they shot.

"His failure to do so resulted in deaths of Cpl. Tillman and the AMF soldier, and the serious wounding of two other [Rangers]," Kauzlarich concluded. "While a great deal of discretion should be granted to a leader who is making difficult judgments in the heat of combat, the command also has a responsibility to hold its leaders accountable when that judgment is so wanton or poor that it places the lives of other men at risk."

The Tillman family complained that questions remained: Who killed Tillman? Why did they fire? Were the punishments stiff enough?

"I don't think that punishment fit their actions out there in the field," said Kevin Tillman, who was with his brother the day Pat was killed but was several minutes behind him in the trailing element of a convoy and saw nothing.

"They were not inquiring, identifying, engaging [targets]. They weren't doing their job as a soldier," he told an investigator. "You have an obligation as a soldier to, you know, do certain things, and just shooting isn't one of your responsibilities. You know, it has to be a known, likely suspect."

And so, in November 2004, acting Army Secretary Les Brownlee ordered up yet another investigation, by Jones.

The result was 2,100 pages of transcripts and detailed descriptions of the incident, but no new charges or punishments. The report, completed Jan. 10, 2005, was provided to the Tillman family. It has not been released to the public; the family found it wanting.

Pressed anew by the Tillmans, the Pentagon inspector general announced a review of the investigations in August 2005. And in March 2006, they launched a new criminal probe into the actions of the men who shot at Tillman.

Coming Sunday: The veteran Pentagon official who is overseeing the latest inquiries has called the Tillman probe the toughest case he has ever seen.