Dignity for Detained Immigrants Act of 2023 This bill directs the Department of Homeland Security (DHS) to establish standards for facilities holding non-U.S. nationals ( aliens under federal law) in its custody, phases out using non-DHS facilities for such purposes, and addresses related issues. The standards must comply with the American Bar Association's Civil Immigration Detention Standards. The DHS Office of Inspector General (OIG) must conduct periodic unannounced inspections of each facility and take various actions against noncompliant facilities, including imposing fines, cancelling contracts, and closing facilities. DHS must report to Congress any death of an individual in its custody within 24 hours and conduct an investigation within 30 days that identifies policy changes that could reduce the likelihood of such a death. DHS may not contract with third parties to operate detention facilities or alternatives to detention programs and must terminate existing contracts within three years of the bill's enactment. The bill establishes that OIG facility inspection reports and contracts for an outside entity to operate a detention facility are records available to the public under the Freedom of Information Act. DHS must maintain certain information relating to immigration-related detention, including the detained individual's location and whether the individual was separated from family. The bill provides for various requirements and procedures related to immigration-related detention, including (1) prohibiting DHS from detaining children, (2) imposing a presumption that a detained individual should be released, and (3) establishing that individuals in custody shall be subject to the least restrictive conditions. The bill also abolishes mandatory detention for asylum seekers.