Ok, debunk this exert from the rebuttal:
An Army surgeon at William Beaumont Army Medical Center removed a bullet fragment from the drug smuggler's right thigh on March 16, 2005. At 7:45 p.m. that evening, Christopher Sanchez, an investigator with the Department of Homeland Security's Office of Inspector General,took Aldrete-Davila and the bullet fragment to his personal residence for the night. This negligent action broke the chain of custody for this vital piece of evidence. The following day, Christopher Sanchez submitted a bullet fragment to the Texas Department of Public Safety for testing. The report concluded that "[t]he copper-jacketed bullet was fired from a barrel having six lands and grooves inclined to the right. The manufacturer of the firearm that fired the copper-jacketed bullet is unknown, but could include commonly encountered models of 40 S&W caliber FN/Browning, Beretta, Heckler & Koch, and Ruger pistols." During the testing of the bullet fragment, the lab technicians destroyed all traces of DNA on it, eliminating the possibility of proving that it came from the drug smuggler's body. These careless actions needlessly cast suspicion on this aspect of the prosecutions case.
They didn't need DNA from the bullet, it was taken out of his body. Unless you think that Davilas was a body double.
Or maybe the suggestion (and it's only a suggestion here, you've really said nothing about what you were TRYING to prove with this section, other than that someone didn't do good police work) is that they replaced the bullet from his body with a different bullet that would trace back to Ramos.
Except that nobody is disputing that Ramos shot at the guy (and hitting him wasn't a criteria for their criminal charges). And if they switched bullets, they did a lousy job, because the bullet was inconclusive to match with the gun (which again didn't matter because nobody disputes that Ramos shot at the fleeing suspect).
So what exactly is this supposed to "rebut"? What does not having a "good chain of evidence" for the bullet do to the case against Ramos and Compean, which is based on their own testimony that they shot at the guy.
BTW, I'm not even certain anybody was trying to keep a "chain of evidence", nor am I certain that an investigator holding the bullet "violated the chain of evidence" although to my untrained mind it could.
And in fact, the summary of your section spells out the entire problem with the pro-BP crowd: "These careless actions needlessly cast suspicion on this aspect of the prosecutions case."
Except "needlessly" is more to the point "meaninglessly".