05/30/2012 12:50 pm ET Updated Jul 30, 2012

Were Trayvon Martin Witnesses Coached to Change Their Stories?

Four key witnesses to the deadly encounter between Trayvon Martin and George Zimmerman gave statements to the police shortly after the occurrence that appeared to support Zimmerman's claim that he fatally shot Martin in self-defense. However, when these witnesses were re-interviewed by agents of the special state prosecutor weeks later, they changed their stories in ways that weakened Zimmerman's self-defense claim. Although it is not unusual for witnesses when re-interviewed to remember new details, reconcile inconsistencies, or even contradict statements originally made, the fact that all of these witnesses changed their original accounts -- given to the police when their memory of the event was fresh and they were not being interviewed by prosecutors trying to build a homicide case against Zimmerman -- raises the troubling implication of improper witness-coaching. Here are the original accounts and altered versions of these witnesses (witness numbers used are for my purposes only, and do not necessarily reflect the witness numbers assigned to these individuals by the prosecutor in the larger case materials):

Witness 1
Original story: Witness saw two persons scuffle but didn't know "which one" was on top of the other during the scuffle.

New story: Witness says she is sure it was Zimmerman on top.

Witness 2
Original story: Witness spotted Zimmerman with "blood on the back of his head." Zimmerman told this witness that Martin "was beating up on me, so I had to shoot him."

New story: Witness describes Zimmerman's demeanor as nonchalant, "More like, 'just tell my wife I shot somebody' like it was nothing."

Witness 3
Original story: "I saw two guys running. Couldn't tell you who was in front, who was behind." After stepping away from her window, she looked again and "saw a fistfight. Just fists. I don't know who was hitting who." In a second interview by police, she stated that during the chase, the two figures were 10 feet apart.

New story: She did not see two people running, just one person, whom she heard more than saw. "I couldn't tell you if it was a man, a woman, a kid, black or white. I couldn't tell you because it was dark and because I didn't have my contacts on or glasses. I just know I saw a person out there."

Witness 4
Original story: Witness states that on the night of the shooting that Martin was on top, "just throwing down blows on the guy, MMA-style." Witness also recalled that Zimmerman was calling for help.

New story: Witness tells prosecution he isn't sure who was calling for help.

Do these changes suggest improper coaching? To be sure, a person's memory is not like a video camera. It is not unusual for witnesses when re-questioned about an event to remember new details, recall certain facts differently, and even forget critical facts. Interviewing is a complex process that requires skill, patience, and objectivity. The fact that key witnesses in the Trayvon Martin case altered their original accounts by itself is not a reason to suspect improper conduct of the interviewers. However, the fact that all of these witnesses changed their stories in ways that appear to strengthen the prosecution's case against George Zimmerman is very troubling.

Witness coaching is one of the "dark" -- some call it "dirty" -- secrets in the U.S. adversary system. Lawyers, police, investigators coach witnesses. They do it by giving cues and suggestions to change recollections, fill in gaps in memory, resolve ambiguities, eliminate contradictions, sharpen language, create emphasis, and alter demeanor. Private lawyers coach witnesses because they are partisans who represent clients and want to win. But prosecutors don't have clients. Prosecutors are supposed to seek justice, not scalps. So coaching is a practice that a prosecutor more than any other lawyer has a duty to avoid. But many reported cases, even in the Supreme Court, describe the conduct of some unscrupulous prosecutors in coaching witnesses to give false, misleading, or exaggerated testimony to enhance their chances of getting a conviction, sometimes of innocent people.

That several witnesses in the Trayvon Martin case changed their stories is troubling for several reasons. First, whereas most prosecutors seek to build strong cases, there is a concern that special state prosecutor Angela Corey may not be a disinterested seeker of justice. Indeed, she has been criticized as an overzealous champion of victims, who prayed with the Martin family over their loss. Many prosecutors have that image. But having an aggressive victim-oriented persona suggests that Corey and her staff may have re-interviewed these witnesses not with the neutral purpose to seek impartial justice but with the self-serving purpose to bring murder charges against Zimmerman. Moreover, the Probable Cause Affidavit filed by Corey which charged Zimmerman with second degree murder contains several large gaps in proof that the prosecution would need to fill to get a conviction. The affidavit states several times that Zimmerman "followed" Martin, "confronted" Martin, and "shot" Martin. But it says nothing about what happened between "followed," "confronted," and "shot." The original statements of the four witnesses would have filled these gaps with circumstantial evidence arguably inconsistent with second degree murder -- witness 1 said she didn't know who was on top during the fight; witness 4 said that Zimmerman was calling for help; witness 3 said she saw two persons running and then saw a fist fight. After being re-interviewed by prosecutors, witness 1 said Zimmerman was on top; witness 4 said he didn't know who was calling for help; witness 3 suggested that she didn't see a fight, and that she barely saw but mostly heard only one person, not two.

Further, given a prosecutor's considerable power and prestige, witnesses typically look up to the prosecutor as a law enforcement expert who can be trusted to use facts responsibly. In such a setting, a prosecutor has a unique ability to persuade, suggest, and even manipulate a witness into altering a story. The witnesses almost certainly knew that the prosecutor was specially appointed to investigate the Trayvon Martin killing, that the case had attracted national attention, that there was the suggestion of a cover-up by the Sanford police to protect Zimmerman, and that they were being re-interviewed to assist the prosecution in bringing criminal charges against Zimmerman. Coaching does not necessarily happen overtly. It often happens covertly, subtly, and sometimes even unwittingly. Although we do not know the extent to which these witnesses may have been vulnerable to a prosecutor's suggestions, the new fact added by witness 2 -- describing Zimmerman's demeanor moments after the shooting as nonchalant -- is a questionable opinion as a matter of evidence law, highly prejudicial to Zimmerman, and almost certainly suggested in a leading manner by the interviewer. But absent any record of how a prosecutor or investigator may have interacted with the witness prior to and during the interviewing session, it is unlikely that improper coaching could be demonstrated. And even if the actual interview is recorded, as some of these interviews apparently were, there is no record of what transpired before the interview session, and what suggestions the interviewer may have made.

The changes by these witnesses are a troubling development in this most controversial case. Given the complex nature of memory, the ambiguity and uncertainty of "facts," and the distorting effects of being questioned and re-questioned about an event, it is possible that the recollection of these witnesses -- the original and altered versions -- may be a combination of an accurately retrieved, inaccurately reconstructed, and an outright imagined memory. The fact that these witnesses have given inconsistent accounts may impair their credibility in the eyes of a jury. But if their newer versions are accepted by a jury, then the prosecutor's chances of getting a conviction have been improved. We're therefore left with the nagging suspicion that these witnesses may have been consciously manipulated by the prosecution to produce just that result.