Unidentified decedents

Unidentified decedent or unidentified person (also abbreviated as UID or UP) is a term in American English used to describe a corpse of a person whose identity cannot be established by police and medical examiners. In many cases, it is several years before the identities of some UIDs are found, while in some cases, they are never identified. A UID may remain unidentified due to lack of evidence as well as absence of personal identification such as a driver's license. Where the remains have deteriorated or mutilated to the point that the body is not easily recognized, a UID's face may be reconstructed to show what it had looked like before death. UIDs are often referred to by the placeholder names "John Doe" or "Jane Doe".

There are approximately 40,000 UIDs in the United States, and numerous others elsewhere. A body may go unidentified due to death in a state where the person was unrecorded, an advanced state of decomposition or major facial injuries.

Some UIDs die outside their native state. The Sumter County Does, murdered in South Carolina, may have been Canadian.Barbara Hess Precht died in Ohio in 2006 but was not identified until 2014. She had been living as a transient with her husband in California for decades but returned to her native state of Ohio, where she died of unknown circumstances. In both of these cases, the UIDs were found in a recognizable state and had their fingerprints and dental records taken with ease. It is unknown if the Sumter County Does' DNA was later recovered, since their bodies would require exhumation to recover DNA. In Lourdes, France, a corpse believed to have been native to a different country was discovered. Many illegal immigrants that die in the United States after crossing the border from Mexico remain unidentified.

Many UIDs are found long after they die and have decomposed severely. This significantly changes their facial features and may prevent identification through fingerprints. Environmental conditions often are a major factor in decomposition, as some UIDs are found months after death with little decomposition if their bodies are placed in cold areas. Some are found in warm areas shortly after death, but hot temperatures and scavenging animals deteriorated the features. In some cases, warm temperatures mummify the corpse, which also distorts its features, though the tissues have survived initial decomposition. One example is the "Persian Princess", who died in the 1990s but, in an act of archaeological forgery, was untruthfully stated in Pakistan to have been over 2,000 years old. A man found in Idar-Oberstein, Germany, in 1994 had died months before his body was found, yet in some places, his skin had not deteriorated and tattoos were found, which are also used to identify the dead.

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