Ammunition manufacturers are in the process of removing lead from their bullets--a new development that experts say could threaten law enforcement's ability to arrest and convict criminals.
On television, crime scene investigators make science seem so simple. In reality, their job is very difficult. Their conclusions are based on complex calculations.
"This is a potential game changer," predicts Michael Knox, a seasoned crime scene investigator. Knox is based in Jacksonville, but consults on cases nationwide, including the Trayvon Martin killing in Sanford.
Knox said he believes the absence of "lead" from bullets and "lead residue" from crime scenes will threaten public safety.
"If we can't prove a case, it's very possible that a suspect will walk out the door and commit another crime," he said.
Right now, investigators can reconstruct most gun crime scenes because they know how lead bullets perform in every conceivable situation. The science is foolproof and accepted in every court.
Knox said investigators have no idea how lead-free bullets will react when fired. There is little acceptable science because lead free bullets are so new; certainly nothing any court would rule admissible -- yet.
"We have to have some idea of what we're looking for (at a crime scene)," says Knox, "or we could miss (evidence that would point to a shooter) all together."
That's where Dr. Michael Sigman from the National Center for Forensic Science, based at the University of Central Florida, comes in.
"One of the ways to identify the shooter and also get information about the bullet is to get residue from the powder," says Sigman.
Sigman and his team are analyzing the already known lead-free bullets available to determine what they're made of. They have already made one vital discovery; Ammunition makers are not replacing lead with another universal material.
"Each manufacturer is using their own combination of metals or materials or alloys for that particular bullet," says Knox. "And they're not sharing that information. It's proprietary information like Coca Cola doesn't share its receipt for its beverages."
This means crime scene investigators, instead of testing for lead, will have to test for an infinite number of chemical compounds. That will increase the amount of time and effort because there will likely be dozens of different kinds of bullets available.
But knowing what a bullet is made is just the start.
"We don't even know if we're even going to be able to develop testing, particularly field testing, that we can use for these various metals," Knox said.
So scientists, Knox says, will have to first develop those field tests then prove they are valid. The scientific community will then have to accept the new methodology. Finally, the testing will have to withstand challenges in court.
Knox says this process will take years. With lead bullets, there is established field testing that is accepted both by the scientific community and the courts.
When lead-free bullets become common, Knox says there will be a criminal advantage that could let dangerous people get away with murder.
"You have the potential to have somebody out there who has already committed one gun crime be free to commit more," Knox said.
Local 6 reached out to several local police chiefs and sheriffs, but found no one that would comment.
Not only will law enforcement have to deal with these new lead-free bullets when investigating crimes, they will also have to research and decide which lead-free bullets their officers and deputies will use. Knox says police want a bullet that will stop an approaching threat, but will do no harm to anyone nearby.
Over the last several years, there has been increasing concern about lead exposure to people who spend a lot of time at indoor gun ranges. So the response is to develop a "green" bullet.