Can DNA spread during washing?

Yes.

DNA can transfer between items during washing, particularly where multiple garments are laundered together.

Washing may reduce DNA on an item, but it does not guarantee removal. Biological material can move between garments through contact, agitation, water movement, and shared laundering conditions. Research has also shown that sperm cells can be transferred from one garment to another during laundering, meaning that semen-related material may appear on items that were not directly involved in the original contact.

Laundering does not end when the wash cycle finishes. Clothing is typically handled during removal from the machine, drying, folding, and storage. Each of these stages presents further opportunities for DNA to be deposited onto a clean item through hands, contact with other garments, or shared surfaces.

Laboratory testing may detect DNA on clothing after washing, but it cannot determine whether the material was present before laundering, transferred during the wash, or deposited afterwards during handling. The presence of DNA therefore does not establish when or how it was introduced to the garment.