If the arrest was recent
Start with the county jail
Someone just arrested in Nebraska is held in a county jail run by the county sheriff, not in state prison.
County jail rosters are fragmented — some Nebraska sheriffs post an online jail roster, many do not.
Nebraska does NOT use the national VINELink system; instead it runs its own statewide custody-status and victim-notification system, NEVCAP (the Nebraska Victims of Crime Alert Portal).
NEVCAP covers both county jails and state prison (Nebraska DCS): you can look up custody status and register for release/transfer/escape notifications online or by phone (24/7 hotline 1-800-395-2110).
If a person is not shown online, call the county jail's booking/records line.
NEVCAP is Nebraska's statewide equivalent of VINE and pulls custody status for participating county jails and state DCS facilities; individual sheriffs (for example Douglas County/Omaha, Lancaster County/Lincoln) may also post their own jail roster. Use NEVCAP or call the county jail directly.