I'm far more than cynical, which was really a compliment to how I feel about this type of rubbish for evidence -- more than a few trial judges would allow an alleged expert to testify to what made the image or impression.
Impressions are highly subjective and but inkblot material in my book. I am greatly reminded of how such nonsense was used in the first trial of Dr. Sam Sheppard in 1954. On the witness stand, the coroner, Dr. Gerber, described what he found on the bloody pillowcase from the murder bed.
Wonder what his defense attorney was doing during this testimony. You would think Dr. Sheppard would have known there was no such surgical instrument like that that existed.
In the 1954 trial (Sheppard's first trial), William Corrigam was Sam's attorney. He objected over and over to Dr. Gerber's incredible speculation and inability to specifically name the alleged surgical instrument, but, time and again, Judge Blythin overruled Corrigans objections.
The celebrity status of Dr. Gerber, Judge Blythin, chief prosecutor Mahon and each of the jurors was simply incomprehensible. Judge Blythin was not going to let his time on center stage receive anything less than rave reviews from the citizens of Cleveland.
Moreover, the court had selected sixty-four jurors to enter voir dire, and their names were listed in Cleveland's newspapers along with their addresses and phone numbers. The first trial represented verdict by peacocks.
In Sheppard v. Maxwell, 384 U. S. 333 (1966), the Supreme Court destroyed Judge Blythin and cited a 'carnival' atmosphere that surrounded the first trial. If the venue is not changed for Casey's trial and you are interested in a preview of what the Supreme Court would rule, read Sheppard v. Maxwell.
http://supreme.justia.com/us/384/333/case.html