Can DNA move after it is deposited?

Yes.

DNA can move after it has been deposited on a surface or item.

Biological material does not always remain fixed in the location where it was first left. DNA can be redistributed through handling, friction, movement of fabrics, contact with other surfaces, or routine activities such as wearing, washing, packaging, or storage.

Importantly, the process of evidence collection itself can also move DNA. Studies have shown that during the collection of exhibits, the placement of items into evidence bags, and their transport to the laboratory, biological material may shift or be redistributed across a surface. Movement within packaging, contact with bag interiors, and handling during examination can all influence where DNA is ultimately detected.

This means DNA may shift from one area of an item to another, or transfer onto nearby objects or materials after the initial deposition. In some cases, DNA may appear in locations that do not directly reflect where contact originally occurred.

Laboratory testing can detect DNA at a particular site, but it cannot determine whether the material remained in its original position or was moved later. It also cannot establish when any redistribution occurred.