An October 2025 Bibb County arrest thrust scientific evidence, and its reliability or unreliability, into the spotlight.
The Bibb County Sheriff’s Office named a 66-year-old Macon man as a suspect in a 2017 sexual assault after DNA evidence from that case matched a previous rape conviction from 1989. He was immediately charged with rape and taken into custody. A judge subsequently denied bail in the case.
On September 16, 2017, deputies responded to the scene of the crime and gathered evidence, which was later submitted to the Georgia Bureau of Investigation Crime Lab. The breakthrough in the case came after further findings from the submitted evidence, the BCSO said.
“We are dedicated to uncovering the truth, delivering justice, and providing closure to victims and their families, all while upholding the highest standards of integrity and professionalism,” stated the Bibb County Sheriff’s Office Cold Case Unit.
DNA Evidence
This scientific evidence may be the most technically sound and legally persuasive form of scientific evidence. However, like other kinds of proof in this category, DNA evidence is only useful for limited purposes.
The use of DNA evidence in criminal cases goes back some forty years. In the 1980s, British researcher Alec Jefferys discovered that each DNA strand has a unique pattern. He believed his discovery had implications for paternity tests, which it does.
In 1986, authorities asked Jeffreys to confirm that a confessed murderer was the actual killer. DNA tests exonerated him and subsequently pinpointed another suspect, who was convicted and sentenced to life imprisonment the next year.
Prof. Jeffreys’ technique has been continually refined over the years. Furthermore, when jurors hear “DNA evidence,” they immediately think “CSI.”
However, DNA evidence, by itself, is not enough to convict a defendant. This evidence only proves the defendant was at a certain place around a certain time. Frequently, investigators play the DNA card during interrogations, hoping the suspect will confess. Then, the DNA evidence must only corroborate that confession.
Fingerprint Evidence
Use of this evidence in criminal court probably dates back to the assassination of Martin Luther King Jr. in 1968.
Police recovered a sniper’s rifle near the scene and lifted fingerprints off that rifle. Acting on a hunch, FBI Director J. Edgar Hoover ordered technicians to compare those fingerprints with the fingerprint cards of known felons in the area. That investigation pointed to James Earl Ray. Authorities took him into custody shortly before he fled the country.
Since then, the science of fingerprint analysis has advanced by leaps and bounds. Digital fingerprint analysis has transformed an investigation that once took months into an investigation that now takes seconds. Additionally, investigators can now use both latent prints (invisible prints that require processing) and patent prints (visible to the naked eye).
Fingerprint evidence may be more useful to prosecutors than DNA evidence. The state can prove that the defendant held a gun or other object. Additionally, fingerprints have the aforementioned “CSI” quality.
However, fingerprint investigations, especially latent print investigations, have more moving parts than DNA investigations. A good Marietta criminal defense lawyer uses these moving parts to undermine the reliability of the results.
Digital or Electronic Evidence
In Georgia, this category usually includes video evidence, computer search records, and smartphone analysis.
Video evidence might place a suspect at the scene. Video evidence might also capture footage of an offense, giving prosecutors a critical eyewitness. Computer search records could be relevant in domestic violence stalking matters, hate crimes, and certain other offenses, such as terroristic threat cases.
Smartphone analysis may be the most common area. Investigators often look for incriminating text messages or other communications on smartphones. Furthermore, these gadgets are basically tracking devices with communications capabilities. Smartphones automatically connect with the nearest cell phone tower, and these connections are time and date stamped.
The Supreme Court has ruled that individuals have a privacy interest in all smart device content beyond the home screen. The Supremes have also ruled that investigators must obtain search warrants before they review the aforementioned connection data.
Ballistics and Firearms Analysis
Ballistics tests are much like fingerprint analysis. A barrel leaves a fingerprint-type impression on a bullet.
Also much like fingerprint analysis, ballistics analysis has advanced considerably. In the old days, investigators basically used magnifying glasses to compare bullets. Now, they use advanced electron microscopes and other devices that spot minute patterns.
Handwriting Analysis
Back when people actually wrote things by hand, this form of scientific evidence was often the final nail in the coffin of a criminal case. Today, handwriting analysts often examine signatures in document forgery cases, but that’s about it.
This kind of scientific evidence is also somewhat circumstantial. Usually, a Marietta criminal defense lawyer calls an independent handwriting expert to the stand in these cases. Independent experts have much more credibility with jurors than police technicians. The same thing is true in other areas of scientific evidence, including an old reliable, like DNA and fingerprint evidence.
Toxicology Reports
Much like other scientific evidence, toxicology reports identify objective things, such as the presence or absence of certain substances.
However, aside from alcohol concentration, toxicology tests usually don’t indicate whether the subject was under the influence of a substance, at least beyond a reasonable doubt. Toxicology tests are much more important in personal injury and other civil cases, because the burden of proof is lower in civil court.
Trace Evidence
Now, we’re scraping the bottom of the barrel, at least in terms of reliability. Trace evidence usually includes clothing fibers, traces of paint, glass, soil, or gunshot residue, tire tracks, and footprints. Usually, prosecutors cannot connect trace evidence with an individual, at least beyond a reasonable doubt. Traces of hair and blood are a little more reliable because they allow investigators to run DNA tests.
As a rule, scientific evidence is not 100 percent reliable or compelling in criminal cases. For a free consultation with an experienced Marietta criminal defense attorney, contact The Phillips Law Firm, LLC. Convenient payment plans are available.
