Yes, command investigation summaries, such as the report from an AR 15-6 investigation, are generally admissible during an Article 32 preliminary hearing. The purpose of an Article 32 hearing is not to determine guilt or innocence but to determine if there is probable cause to believe a crime was committed and to provide the defense with discovery. Therefore, the rules of evidence are much more relaxed than at a court-martial. Hearsay is admissible, and the investigative report is a form of hearsay.
The government representative at the hearing will often rely heavily on the command investigation summary to present their case to the Preliminary Hearing Officer (PHO). They can submit the entire report, including its summaries, witness statements, and findings, as evidence. This is a primary way that the government presents its case in this preliminary, non-trial setting.
However, the military defense attorney has the right to challenge the contents of the summary. They have the right to call the investigator who wrote the summary as a witness and to cross-examine them about their methodology, their conclusions, and any evidence they may have ignored. The attorney will also call other witnesses to rebut the facts contained in the summary. The PHO will then weigh all the evidence, including the summary and the defense’s challenges to it, to make their final recommendation on probable cause.