FAQs

• A copy of the relevant scientific reports
• An outline of the allegation and case circumstances
• The aspects at issue
• Anticipated trial date and date by which a report is required

Usually the same day as it requested.

Let us have a written instruction together with a copy of the legal aid prior authority (if applicable).

It depends on the amount of work and whether we need to visit the Crown’s laboratory to examine the exhibits or the case notes. The CPS has to give written approval for defence access to the items and/or Crown scientist’s case file. We always aim to meet your required timescales for court.

Yes, we have many years of experience giving evidence in court, often at the Old Bailey. We can also sit in court to advise counsel if required.

Depending on the information available, the expert may be able to give an opinion as to the likely timescales in broad terms. For example that intercourse is likely to have occurred within 2 days rather than 5 days.

No – sexual intercourse can occur without the ejaculation of semen or a condom may have been used.

Sometimes – it depends on the extent of the washing. However washing does make it much more difficult to locate the semen.

Not at the present time, however see also the answer to the next question.

We can evaluate the findings against the prosecution and defence accounts and give an opinion as to how much more likely given one account rather than the other. In some cases we may be able to say its extremely unlikely that the DNA was deposited as a result of a specific scenario.

Indefinitely provided the stain has not degraded. Degradation occurs slowly over time unless a stain is kept moist or warm, so it is usually possible to obtain DNA profiles from dried stains several years old.

This is a new form of DNA profiling which was introduced in 2014, it replaces SGMPlus which had been in use for many years. DNA17 examines 17 areas (or loci) on the DNA and includes a gender test. It is much more sensitive and provides greater discrimination that previous methods. See our post here for more information.

Current methods are extremely sensitive and just a few cells can produce a profile. The stain does not even have to be visible.

Sometimes – this is called ‘attribution’ and is an expert opinion. It involves the scientist taking into account the amount of body fluid, the strength and nature of the DNA profile and the case circumstances.

For a DNA component to be confirmed as part of a profile it must meet certain criteria. DNA components appear as peaks in the raw result and must be of a defined size to be called ‘confirmed’ or be duplicated in a repeat test. When a DNA peak does not meet the required criteria it is called ‘unconfirmed’. Unconfirmed components can provide an indication of what DNA is present but are not used for evidential comparisons or any statistical analysis.

A full or complete DNA17 profile consists of 32 components plus another two indicating the likely gender of the donor. When DNA is present in small amounts or has been degraded, some components may not be seen – this is called a partial or incomplete result.

This is when DNA is transferred onto an item indirectly via an intermediary. This means that DNA from a person can be detected on an item without that person ever having been in contact with it. In some situations, the forensic expert can given an opinion about whether DNA is more likely to be the result of direct or indirect transfer.

Not necessarily – it will depend on the nature of the assault, the amount of bleeding and the extent of contact between the parties. In cases where the expectation of blood transfer to the assailant is high, the absence of blood on a defendant’s clothing will be significant. Whereas in other cases the absence will be neutral evidence.

Yes – expert opinion can be given about the action which caused the blood to be deposited – for example contact, drip, airborne spatter.

Some fibre types are relatively common, for example blue denim fibres. However the tests used when determining whether fibres have come from a particular source are highly discriminating. Fibres can provide strong evidence to support contact between items of clothing or other textile surfaces.