How to Carry Out a DNA Test with a Deceased Person?

A DNA test with a deceased person is sometimes considered when there is uncertainty about a biological relationship, or when no standard sample could be collected during that person’s lifetime. In this situation, the key question is straightforward: which DNA sample is genuinely usable, and under what conditions?

Below are the available options, their limitations, and the administrative points to anticipate if you want to maximise the chances of obtaining a reliable result.

1) Choosing the right sample: the basis of a reliable result

To carry out a DNA test, the choice of sample is critical.

Recommended samples when the person is alive

In kinship testing, laboratories generally recommend sending:

- buccal swabs,

- together with a saliva sample.

“Non-standard” samples when buccal swabs are not possible

In many situations, non-standard samples can also be used, including:

- nail clippings,

- blood samples,

- ear swabs containing earwax,

- or other similar biological traces.

These samples are often easy to collect and can be useful when buccal swabs cannot be obtained.

2) After the funeral: is it still possible to recover DNA?

A DNA test is sometimes considered only after the funeral has taken place. In that case, samples may still be collected under certain conditions in order to obtain the most reliable result possible.

Recovering belongings or traces left by the deceased

The first step is often to look for existing samples that belonged to the deceased person.

Two factors have a major impact on the quality of the analysis:

- how the sample was stored,

- and the time elapsed between the trace being left and the start of laboratory analysis.

In most cases, if the death occurred several years ago, the available samples are more likely to produce a degraded and incomplete genetic profile.

Examples of usable samples (non-exhaustive list)

- Hair with the root attached

- Nail clippings

- A blood stain on clothing or a dressing

- Earwax on cotton buds

- Teeth

- Razor

- Toothbrush

Cost and complexity: why post-mortem testing is often more expensive

Post-mortem genetic testing is usually more expensive, especially because:

- the number of available samples is often limited,

- and their condition at the time of analysis may be poor.

It is also very common for DNA extraction to require several attempts before a complete genetic profile can be obtained.

For that reason, it is generally advisable to send as many usable samples as possible to the laboratory.

3) Consent: an essential issue when using DNA from a deceased person

Who can authorise the use of a sample?

Consent for the use of a deceased person’s sample can generally only be provided by the closest relatives, unless the deceased left written instructions before death.

In practice, the laboratory will usually check:

- the legal family relationship,

- and the death certificate of the deceased participant.

For general guidance on DNA analysis and consent in the UK, you can refer to the Human Tissue Authority guidance on DNA analysis.

Medico-legal cases: when a court order may be required

In medico-legal matters, a court order may be necessary to obtain or use a sample without approval from the next of kin or without prior permission from the deceased, for example in a homicide investigation where DNA testing is needed for clarification.

4) Which samples can be taken directly from a deceased body?

The earlier the sample is collected, the better the chances of obtaining viable DNA, because decomposition damages genetic material. Some samples remain usable only for a short time.

Nails and hair

Nails and hair or body hair with the root attached can often be collected from the body without visible damage.

They may remain suitable for analysis for several months and are often among the simplest options to extract.

Bones and teeth

Bones are among the best samples for preserving DNA. As a general rule:

- the larger the bone, the more likely it is to contain bone marrow,

- and bone marrow can preserve useful genetic material.

Teeth, like bones, are also excellent samples because:

- they remain protected within the jaw,

- they can preserve DNA in the root for a very long time,

- and they can usually be removed relatively easily.

Blood, sometimes retained by funeral professionals

Some funeral professionals may collect and keep a blood sample for a limited period, sometimes for one to two years, either on request or as part of their service arrangements.

One point should be kept in mind: the longer blood is left to dry, the less reliable it becomes for DNA analysis.

Be careful with embalming

Collecting control samples before burial is only possible during a very short period, before embalming begins. Once embalming fluid has been used, it can interfere with the DNA sample and compromise analysis.

5) Exhumation and DNA testing: principle, value and limitations

What is exhumation?

Exhumation means removing a coffin or the remains of the deceased from a grave or burial vault. In England and Wales, this is subject to authorisation and a formal process.

For the official administrative procedure, you can consult the GOV.UK guidance on applying for an exhumation licence.

Why exhumation may be considered for DNA purposes

Exhumation may be considered because there is sometimes a chance that preserved genetic material remains available on or within the body.

However, this is never a straightforward step. The decision must take into account:

- family consent,

- religious restrictions,

- and the law applicable to post-mortem parentage issues.

A procedure that is often lengthy, complex and costly

Exhumation can be:

- lengthy,

- complex,

- and expensive.

The actual condition of the body at the time of exhumation must also be considered. The older the burial, the lower the likelihood of finding usable samples.

6) Can a DNA test be carried out using cremated ashes?

Cremated ashes may sometimes be proposed as a possible sample. They result from cremation, a funerary process that reduces the body to ashes through intense heat. Cremation usually reflects an explicit choice expressed during the person’s lifetime.

Reliability: very low chance of obtaining an accurate result

In practice, testing DNA from cremated remains has very little chance of producing an accurate result because:

- the temperatures used during cremation carbonise the remains to such an extent that the sample becomes highly unreliable,

- and the heat destroys the DNA needed for analysis.

In some cases, a small fragment may remain usable, for example part of a bone, but only where cremation has been incomplete. A laboratory may attempt analysis, but exposure to very high heat makes it far more likely that the sample will not be viable.

Important point: ashes cannot be returned

Ashes sent to a laboratory will be used during the analysis process and cannot be returned to the family. This has to be considered carefully because:

- the test cannot be repeated a second time using the same ashes,

- and you will no longer have the deceased person’s ashes afterwards.

Requested sample quantity for ashes

- Adult man: 2500–3000 g

- Adult woman: 1800–2000 g

In most situations, cremated remains are held by the next of kin, which makes access to the sample easier. Otherwise, a court request may be necessary. In any case, the legal consent of the family must be provided before analysis can be requested from an accredited laboratory.

7) When there is no sample: family reconstruction DNA testing

If samples from the deceased produce no result, or if no sample is available at all, the final option is to carry out DNA testing with close family members.

Part of our DNA is shared with relatives: the closer the relationship, the greater the proportion of shared DNA. To genetically reconstruct the profile of an absent person, it may be useful to include the most relevant relatives, such as:

- grandparents,

- parents,

- aunts and uncles,

- brothers and sisters,

- nieces and nephews,

- grandchildren.

Reliability: direct relatives and participant numbers matter most

The most informative tests are usually those involving direct relatives. Reliability also depends on how many participants are available to help establish the biological relationship.

In a paternity investigation, grandparent DNA testing, avuncular DNA testing, and sibling DNA testing are often the most useful options for reconstructing the father’s genetic profile.

No court or administrative procedure where everyone agrees

These tests do not usually require legal or administrative proceedings if all participants agree to provide their DNA as part of the search for the deceased person’s biological relationship.

A post-mortem DNA test is possible, but its effectiveness depends above all on sample quality, storage conditions and the time that has passed. Whenever possible, it is better to prioritise several types of samples, such as nails, hair with roots, teeth and blood traces, while also anticipating the issue of family consent.

If no usable sample is available, family reconstruction can provide a coherent alternative, especially when several close relatives agree to take part. To move forward as smoothly as possible, the simplest approach is to gather all available materials, choose an accredited laboratory, and prepare the required supporting documents in advance to avoid delays.