Mathilde Libretti was a J.S.C. Officer, who was an agent for Admirel Emm's U.N.S. Intelligence Services.
Book 15: Delegates and DelegationEdit
Libretti was considered a deep sleeper agent. At the start of the events in Sol, she was already married with husband and kids. This was a problem, as Kowalski wasn't skilled enough to act those two roles without being detected, and her husband has to be sent off to a solcruise while she locked in overtime. 
When the Tagon Toughs arrived in Sol as part of the diplomatic team for the Oafa, she was activated, and given the code name Mako.
Her activities were initially to arrest the amorph Schlock. When the M3-tater detonated when Schlock was on route to meet prime tangent Breya Andreyasn, she took the opportunity to blame him as the terrorist only to be commanded otherwise by orders from her superior (and by extension, Breya). Schlock and the rest of the team clammed up, leaving back to the villa. Due to the explsion, Mako's weapon was confiscated and replaced with a new one (although the modification was undetected).
During the night, she was given new orders to investigate the assassination. This was likewise duplicated from orders from Captain Landon. After a quick chase, she got a statement from Lieutenant Sorlie.
There was a crude nanny subjornation attempt from the replacement M3-Tater. She determined that operational intregity was compromized, and asked Doctor Edward Bunnigus to remove the nanites. Within a short time, the faux-rebellion started, and in the chaose, she was placed under command of Sorlie.
Mako sacrificed herself to provide close range targetting information to clear out the faux-rebellion that was attacking the Dom Atlantis armory.