DNA analysis started for the identification of plane crash casualties

News item | 01-08-2014 | 15:05

The NFI obtains DNA profiles from the DNA samples which are taken from both the victims and relatives of the victims by the Dutch National Forensic Investigation Team (LTFO).

DNA analysis forms part of the identification process carried out by LTFO

The DNA analysis forms part of the identification process carried out by LTFO. For the identification, the investigators in Hilversum assess the physical characteristics of the victims, including fingerprints and dental records. Personal belongings, such as clothing and jewellery, as well as any information provided about them, are included in the investigation.

DNA samples taken from victims

During the identification process, the LTFO experts take DNA samples from the victims: bits of muscle tissue, bone tissue or dental elements (teeth or molars). The DNA is best protected from external influence in dental elements. The NFI receives the muscle, bone, tooth or molar samples and from this material DNA profiles of the victims are obtained.

DNA samples taken from relatives

The NFI also receives the DNA samples taken from direct family members by the family police detectives by means of buccal swabs. The family detectives use a small brush on the inside of the relative’s cheek to take the sample. Direct family members are parents, children, brothers and sisters of the victim. DNA samples of these relatives are important for the investigation, because the DNA profiles of these close relatives have a higher degree of similarity than those of distant relatives.

DNA of victims’ personal belongings

The NFI also receives personal belongings containing DNA that was left on them by the victims before they died. Examples are toothbrushes, hairbrushes containing hair or razor blades. These objects may contain the victim’s DNA.

These objects are not always available; the victims may well have had these personal belongings with them at the time of the disaster. Additionally, some caveats are necessary, as it remains to be seen whether the item for personal use actually belonged to the victim and whether it was ever used by somebody else.

Comparing DNA profiles

In order to identify a victim on the basis of DNA, the DNA profiles of the victims are compared with the DNA profiles of their relatives and/or the DNA profiles made on the basis of their personal belongings. DNA is passed down from parent to child. This is why the DNA profiles of family members are more similar than DNA profiles of non-related persons. This is the basic principle of the DNA family relationship test.

Applying Bonaparte

In order to compare the victims’ DNA profiles with the DNA profiles of their family members, the NFI uses a computer programme called Bonaparte, which was developed especially for this purpose.

The DNA profiles of the family members are entered into the Bonaparte programme. If a DNA profile of a victim is available (obtained from an item of personal use), it is also entered into the system. Bonaparte places the DNA profiles of the relatives and those of the victims in the family trees. The computer system then makes a comparison and calculation for each body or body part of the victims and determines whether the DNA profile fits the DNA profiles of the relatives.

If a family tree contains the DNA profile of the victim, obtained from a personal item, Bonaparte will determine which body or body parts match that profile.

Bonaparte also compares the DNA profiles of the bodies and body parts of the victims with each other, to determine whether body parts belong to the same victim and whether there is a family relationship between victims.

Identification on the basis of correlation between results

On the basis of the correlation between all results of all identification processes - special external features, fingerprints, dental records and DNA profiles - the remains will eventually be identified by the LTFO.