( weeks it became obvious that many rem...)World Trade Center identifications pushed forensic DNA technology

Until Septenber 2001, crime labs across the country generally used STRs ?short tandem repeats ?in forensics work. STRs are biological markers in nuclear DNA that are inherited from both parents and vary widely among people. The Combined DNA Index System ?CODIS ?used by the FBI, uses 13 of these markers for identification purposes. Shaler's group used up to 16 markers. If sufficient markers matched known DNA samples, then there was an identification.

However, to do any matching, analysts needed DNA samples from the missing individuals including toothbrush, hairbrush and razor samples and DNA samples from close relatives. The New York City Police Department obtained these reference samples.

Collecting and recording large numbers of samples perfectly is difficult. Errors and omissions occur. Throughout the investigation, the OCME maintained contact with families of the victims and worked with them. The contact brought perspective to the project, friendships and, at times, emotional turmoil.

"Working with the families is critical to getting the job done properly, and the truth is that the medical examiner and the police need to establish a synergistic relationship from the outset," said Shaler.

Certainly in this emotional, heart-wrenching environment, patience and understanding were aided by familiarity and trust.

While samples of the living are replaceable, it quickly became apparent that degraded DNA made the use of STR by itself impossible in many victim identifications.

Shaler and colleagues decided to look at two other DNA methods -- mitotyping and SNPs. Mitotyping involves looking at mitochondrial DNA, DNA inherited only from the mother, and comparing it to a standard reference. While mit
'"/>

Source:Penn State