unaccounted foradjective
/ˌʌn.əˈkaʊn.tɪd//-t̬ɪd/If a person is unaccounted for, it is not known where they are or whether they are still alive:
A fire on the ship killed a hundred or more passengers - some likely victims are still unaccounted for.
If something such as an amount of money is unaccounted for, it is not present and there is no explanation for what has happened to it:
An audit of the police department found that $100,000 in cash and one handgun were unaccounted for.