WASHINGTON — An investigation into allegations the Marine Corps delayed sending blast-resistant trucks to Iraq also will examine whether the Marines were negligent in delivering a laser to divert drivers and people from checkpoints and convoys, according to a memo obtained by AP.

Marines on the front lines sought the tool, known as a Compact High Power Laser Dazzler, but stateside acquisition officials didn’t deliver it, a civilian Marine Corps official said. A less capable laser was eventually sent, but delays of nearly 18 months may have led to an untold number of Iraqi civilian casualties, according to allegations by the official, an internal critic whose claims are being investigated.

The deaths and injuries occurred when civilians mistaken as the enemy got too close to guarded areas and American troops lacked a non-deadly way of forcing them away, according to the official. The Iraqi government has complained about such incidents in the past.

The Dazzler emits a powerful stream of green light that stops or redirects oncoming traffic by temporarily impairing the driver’s vision. Without it, troops have to open fire when warning signals are ignored or not seen.

The Marine Corps has stressed that the allegations made by the official, Franz Gayl, reflect his personal views.

Mr. Gayl’s conclusions stem from a series of case studies he was conducting for the Marine Corps plans, policies, and operations department about the wartime acquisition system.