The Graveyard Shift

Archive for the ‘Evidence’ Category

It’s frustrating to spend hours, maybe days, working a criminal case only to see your suspect walk out of jail moments after booking is complete. A quick phone call to a bondsman and off they go. Now, if officers had rock-solid evidence, such as DNA, judges wouldn’t be so quick to release offenders back to the streets where they may commit another crime before their court date.

Thanks to Andrew Hopwood at the Forensic Science Service and Frederic Zenhausern from the Center for Applied NanoBioscience and Medicine in Arizona, the days of pre-trial revolving door justice may soon be a thing of the past.

These two scientists have developed an impressive device that allows technicians to simply obtain a cheek swab (DNA sample), test it, and presto…four hour DNA results!

Photo by FREDERIC ZENHAUSERN/Analytical Chemistry ACS Publications

The test is actually fairly simple. As stated, technicians swab the inside of the suspect’s cheek, mix the sample with a solution, and and then place it on a special platform (a chip) inside the machine. The platform (microfluidic platform) extracts the DNA, amplifies it (makes exact copies), and then, through laser electrophoresis (remember, the old method used gels and later a genetic analyzer—still electrophoresis, only slower) the DNA can be compared to a victim, suspect, or other evidence.

And all this is completed in just four short hours! Older methods of DNA testing sometimes required a period of approximately 24 hours simply to extract DNA from the evidence. This method required the sample to soak in an enzyme at least overnight before scientists could begin the actual testing.

Hopwood and Zenhausern are now hoping to reduce turnaround time of their already lightening-fast chip (the platform) and dip (the swabbing) system to a mere two hours!

If only they could do something about the laboratory backlogs…

In the past, experts have traditionally determined the sex of skeletal remains by examining characteristics of the pelvis—the pubis is larger in females; the ischium is larger in males. Simple as that. Or, is it?

Suppose the forensics team has mere fragments to study? What if only a portion of the pelvis is available? How about if they only have as little as fifteen percent of the pelvis?

Well, scientists at North Carolina State University have come up with a better, more accurate method of separating the boys from the girls. They’ve learned that there are 20 distinct areas (landmarks) on a pelvis that can be used for sex determination. This was a huge discovery because it meant that even a small section of a pelvis would contain at least some of those distinguishable trademarks. And, to add to this icing on the cake, the new method touts a 98% accuracy rate as compared to a 90% success rate using the standard method of visually examining the bone(s).

Now to be a little more specific about how the process works (easy as 1-2-3). First, a 3-D image is fed into a digitizer, which measures the landmarks on the bone fragment. Then those measurements are compared to a standard. Next…the results. It’s a girl! Pass the cigars.

This new development is terrific news for prosecution and defense teams. Not only do each of them have more accurate results to present to judges and juries, they no longer have to rely on opinion. Defense attorneys won’t need to try and make the forensic anthropologist look like a babbling idiot, and the prosecutor won’t have to make them out as gods. It’ll all boil down to the reliability of a computer and the research of two North Carolina State scientists—Dr. Ann Ross and Dr. Joan Blytheway.

Dr. Ann Ross, on right, with students at NC State

But, this may have all been a huge waste of time. All anyone had to do was ask any teenage boy to identify the bones. After all, they’re pros at determining sex by examining hips.

And here’s a page from their secret handbook to prove it. (Please turn on your audio).