COMMON CAUSES OF ERRONEOUS CONVICTIONS

Wrongful convictions may seem the result of random human error, but common factors suggest they are produced by something more than chance, defense lawyers and advocates say. Here are some of the common elements:

*The offense. Heinous crimes and violence against women and children generate large-scale news media coverage and charge public emotions. Pressure is intense on prosecutors and police to find and convict someone of the crime.

*Zeroing in. Under pressure, police latch onto something, perhaps a quirk of behavior, that causes them to target an innocent person as the prime suspect. Only then do police begin building a case, often minimizing or ignoring evidence that points to other suspects while exaggerating the importance of other clues.

*Suppression of evidence. Prosecutors or police hide from the defense and the jury certain evidence or testimony that contradicts or undercuts their claim that the defendant is guilty.

*Sloppy police work. Crucial evidence, usually supportive of the defendant, is lost, overlooked, misconstrued, suppressed. Other evidence supportive of the prosecution is exaggerated or falsified.

*Sloppy defense lawyers. Low-paid, overworked public defenders often fail to point out flawed prosecution arguments.

*Jail-house confessions. Alleged confessions of guilt that are allegedly witnessed by undercover officers or inmates who are offered a deal by prosecutors in exchange for their testimony. Not infrequently the existence of the deal is unknown to a defendant's attorney and to the jury.

*Misidentification by eyewitnesses. Many times eyewitnesses who did not get a good look at an attacker are encouraged or even coached by police to identify a particular person.

*Prejudicing the public. When evidence is thin or inconclusive, labeling and tarring a defendant through the news media can sometimes help a jury convict and help police rationalize the arrest.

*Spurious ''scientific'' evidence. Forensic evidence subject to wide interpretation is offered by ''expert'' witnesses as conclusive.

*Biased judges. A judge may bias a jury by his comments or orders. Lawyers for falsely convicted Canadian Guy Paul Morin charge that the judge tilted toward the prosecution in numerous instances.