Two senators want to know the status of information on the suicide rate for military family members, data the Pentagon was ordered to start collecting in 2014.

Defense officials were ordered to standardize and collect that data as part of a larger measure on military suicide included in a 2014 law. And while the Pentagon has fulfilled the request for service member suicide data, it seems to have ignored the order to include military dependents, according to a letter sent by the senators to the Defense Department.

The letter, signed by Democratic Sens. Patty Murray of Washington and Tim Kaine of Virginia, was sent July 12 to Defense Secretary Jim Mattis.

"While the Department made significant progress in the intervening years to address service member suicide, it appears there is still no reliable system across all services for collecting data on dependent suicide," the letter states. "We ask that the Department of Defense release any data on military dependent suicide, and we urge you to work with Congress to take action to address these concerns."

The new policy had been due no later than Dec. 19, 2014. But no official report or update on the results of the family member portion of policy has been released.

Military family member suicide rates are notoriously difficult to track and report, largely because the Pentagon in the past did not have a standard method for collecting the information. For example, death by suicide among military families that occurs on base might be tracked, but those that occur off base often are not.

A sweeping report on military suicide known as the Defense Suicide Report (DODSER) was released July 2, but doesn't include information or even a reference to suicide rates among military family members.

That lack of information hamstrings the department's ability to respond to the problem, the letter says.

"We know these suicides occur, but there is presently a lack of information necessary to understand, prevent, and respond to these tragedies. We understand that collecting suicide data on military dependents can be especially challenging compared to collecting similar data on service members, but in absence of clear data, this problem cannot be effectively understood or treated," the letter notes.

Pentagon officials did not respond to Military.com requests for an update on the data.

-- Amy Bushatz can be reached at amy.bushatz@military.com.