This thread here
I am currently deployed to Mosul with one of the Field Artillery batteries-turned-Military Police companies, and have often asked myself the same questions.
This is the second story of this sort that I have had personal involvement with (the first being the 4 missionaries who were killed back in March), and I still can't figure out why unarmed US citizens feel the need to wander through decidedly unfriendly territory.
I can give some personal observations about the story you referenced above:
However, Senor said Iraqi police arrested Berg in Mosul on March 24 because local authorities believed he may have been involved in "suspicious activities."
Fact. Mr. Berg was never detained by Coalition forces - he was detained by Iraqi police when the taxi he was riding in was stopped at a checkpoint and he refused to produce identification.
"U.S. authorities were notified," he said.
Fact. The MP liaison team at Mosul police headquarters talked to Mr. Berg within minutes of his being brought in, this was passed on to higher headquarters immediately.
"The FBI visited Mr. Berg on three occasions and determined that he was not involved with any criminal or terrorist activity."
Fact. They also recommended that he leave the country, as stated in the story.
In Mosul, however, police told the AP they had no knowledge of the Berg case. Police official Safwan Talal said the only American arrested there in recent months was a woman who was released soon afterward.
Half-truth. The Iraqi police may not know anything about the Berg "case" per se - he was never arrested and prosecuted in an Iraqi court, but they definitely know that he was held in one of their police stations for two weeks. The "American" woman was in fact Swiss, and detained for the same reason - "suspicious activities." She was released after a background check was made.
Since Iraq remains under U.S. military occupation, it seems unlikely that the Iraqi police would have held Berg, or any other American, for such a length of time without at least the tacit approval of U.S. authorities.
Fact. The Iraqi police were directed to hold Mr. Berg until the FBI was able to get a team to Mosul to question him.
Kimmitt said U.S. forces kept tabs on Berg during his confinement to make sure he was being fed and properly treated because "he was an American citizen."
Fact. He was checked 3-4 times daily by MPs from my unit (who also brought him his meals, bottled water, reading, and writing material).
What happened to him after his release is open to speculation, that is where my involvement in this story ends. Whatever the true reason he was in Iraq, he did not deserve what ultimately happened to him.