WASHINGTON – The Pentagon is coming under pressure to give Congress detailed information on the handling of sex crime cases in the armed forces following an Associated Press investigation that found a pattern of inconsistent judgments and light penalties for sexual assaults at U.S. bases in Japan.

Democratic Sen. Kirsten Gillibrand of New York, who's led efforts in Congress to address military sexual crimes, is pressing the Defense Department to turn over case information from four major U.S. bases: Fort Hood in Texas, Naval Station Norfolk in Virginia, the Marine Corps' Camp Pendleton in California, and Wright-Patterson Air Force Base in Ohio.

Such records would shed more light on how military commanders make decisions about court martials and punishments in sexual assault cases and whether the inconsistent judgments seen in Japan are more widespread.

AP's investigation, which was based on hundreds of internal military documents it first began requesting in 2009, found that what appeared to be strong cases were often reduced to lesser charges. Suspects were unlikely to serve time even when military authorities agreed a crime had been committed. In two rape cases, commanders overruled recommendations to court-martial and dropped the charges instead.

Gillibrand, who leads the Senate Armed Services personnel panel, wrote Monday to Defense Secretary Chuck Hagel asking for "all reports and allegations of rape, forcible sodomy, sexual assault, sex in the barracks, adultery and attempts, conspiracies or solicitations to commit these crimes," for the last five years.

She said AP's investigation is "disturbing evidence" that some commanders refuse to prosecute sexual assault cases and the Pentagon should have provided the records more quickly.

The documents may build momentum for legislation she has introduced that would strip senior officers of their authority to decide whether serious crimes, including sexual assault cases, go to trial. The bill would place that judgment with trial counsels who have prosecutorial experience and hold the rank of colonel or above. The legislation, expected to be voted on in coming weeks, is short of the 60 votes needed to prevent a filibuster.

Defense Department officials have acknowledged the problem of sexual assaults in the ranks and said they are taking aggressive steps to put a stop to the crimes.

"This isn't a sprint," said Jill Loftus, director of the Navy's sexual assault prevention program. "This is a marathon and it's going to take awhile."