This is the doctrine

Not that it matters much, but this is what the Schoolhouse teaches (and has taught since 1987) on treatment of EPWs.

FM 34-52 Chapter 6

SUPPORT RELATIONSHIPS

Successful interrogation operations require support from a number of elements within their echelon of assignment, including all of the major staff organizations. These elements are collectively responsible for the planning that creates the overall environment for interrogators. The intelligence staff's (G2 or S2) direct contribution to interrogation operations has already been discussed. Its general responsibilities are outlined below, along with those of other staff and support elements.


The G1 and S1 are responsible for: supervising the medical support furnished to sources, maintaining a list (by language and proficiency) of qualified linguists within their command, and coordinating with the G5 for procurement and payment of other interpreters and translators needed to perform both intelligence and nonintelligence duties. The G1 and S1 ensure that the echelon's operations plan contains complete provisions for source handling and evacuation. This plan must satisfy the interests of all other staff officers, as well as STANAG 2044 (see Appendix A for an extract). Its provisions must cover the following principles:


Humane treatment of all sources.
Prompt evacuation from the combat zone.
Opportunities to interrogate sources.
Integration of procedures for the evacuation, control, and administration of sources with other combat support and combat service support (CSS) operations (through the provost marshal).
Training for all troops on the provisions of international agreements and regulations relating to sources.

Which means either the MPs lied, or the Officers were criminally negligent in the performance of duty. Or both.



As for things, like the review of procedures, and the long term care

ADDITIONAL SUPPORT

Besides the major staff elements, an interrogation element requires support from several other elements in order to conduct operations. These elements include-


Communications. Secure, reliable communications must be available at or near the interrogation element's deployment site. Priority access to these communications must be arranged to support contact with collection management.
Staff judge advocate. This element can provide legal support and advice on the interpretation and application of international regulations and agreements concerning handling of sources. It is also a channel for reporting known or suspected war crimes.
Health service support. This element must clear all sick and wounded sources before they can be interrogated. Seriously sick and wounded sources are evacuated through medical channels. If adequate facilities are not available in EPW hospitals, EPWs are admitted to military or civilian medical facilities where the required treatment can be obtained. Medical inspections are made and the weight of each EPW is recorded at least once a month. Provisions are made for the isolation of communicable cases, for disinfection, and for inoculations. Retained medical personnel and EPWs with medical training are used to the fullest extent in caring for their own sick and wounded. FM 8-2 and FM 8-10 provide guidance for health service support.
NBC protection. All EPWs will be provided NBC protection. EPWs should be allowed to use their own NBC protection equipment or if not feasible, the detaining forces will exchange the EPWs' equipment for proper NBC gear. If EPWs do not have their own NBC protection equipment, the detaining forces must provide them with proper NBC gear.
Chaplain support. The unit ministry team, chaplain, and chaplain assistant provide for religious support. Coordination is made with the S5 and G5 for religious support for refugees, displaced persons, and indigenous civilians. The unit ministry team provides for services for EPWs or assists by supporting detained clergy of enemy forces, supporting other detained clergy and providing for burial rites (combatants are granted, where possible, the right to be buried according to the rites of their religion). Religious preference of EPWs will be obtained from their detainee personnel record form (see Appendix B).
Inspector general. This element is a channel for reporting known or suspected war crimes.


Regrettably, Miller seems to think the basic situation is fine, and these are just bad actors. Which means, I afraid, this will all happen again.

Punishment

For those contractors, the ones everyone seems to think are immune because they aren't in the Army, and weren't in the states.

Sec. 3261. - Criminal offenses committed by certain members of the Armed Forces and by persons employed by or accompanying the Armed Forces outside the United States


(a)

Whoever engages in conduct outside the United States that would constitute an offense punishable by imprisonment for more than 1 year if the conduct had been engaged in within the special maritime and territorial jurisdiction of the United States -

(1)

while employed by or accompanying the Armed Forces outside the United States; or

(2)

while a member of the Armed Forces subject to chapter 47 of title 10 (the Uniform Code of Military Justice),


shall be punished as provided for that offense.

(b)

No prosecution may be commenced against a person under this section if a foreign government, in accordance with jurisdiction recognized by the United States, has prosecuted or is prosecuting such person for the conduct constituting such offense, except upon the approval of the Attorney General or the Deputy Attorney General (or a person acting in either such capacity), which function of approval may not be delegated.

(c)

Nothing in this chapter may be construed to deprive a court-martial, military commission, provost court, or other military tribunal of concurrent jurisdiction with respect to offenders or offenses that by statute or by the law of war may be tried by a court-martial, military commission, provost court, or other military tribunal.

Sec. 3262. - Arrest and commitment


(a)

The Secretary of Defense may designate and authorize any person serving in a law enforcement position in the Department of Defense to arrest, in accordance with applicable international agreements, outside the United States any person described in section 3261(a) if there is probable cause to believe that such person violated section 3261(a).

(b)

Except as provided in sections 3263 and 3264, a person arrested under subsection (a) shall be delivered as soon as practicable to the custody of civilian law enforcement authorities of the United States for removal to the United States for judicial proceedings in relation to conduct referred to in such subsection unless such person has had charges brought against him or her under chapter 47 of title 10 for such conduct

For more details (such as specific offenses) look at
http://www4.law.cornell.edu/uscode/18/3261.html

As for what they shuold face

Sec. 2441. - War crimes
(a) Offense. - Whoever, whether inside or outside the United States, commits a war crime, in any of the circumstances described in subsection (b), shall be fined under this title or imprisoned for life or any term of years, or both, and if death results to the victim, shall also be subject to the penalty of death.