Lieutenant David LaSalle is Specter Team's squad leader and a Sentinel. He works for SRPA and sends the organization pictures and intelligence of Chimeran facilities, weapons, creatures, and machines. He is only mentioned in intel documents in Resistance 2 and Resistance: Retribution.
LaSalle appears to be stationed in Europe and was involved in many recon work, which he and Specter Team were partially responsible for many of SRPA's new technological achievements. In July 1951, LaSalle discovered a Chimeran construction zone in Gerolstein, Germany, and taking many photographs on the area and sending them to SRPA Station Igloo in Iceland for analysis. He had also helped in acquiring Gray Tech components around Europe with the help of the Maquis.
In Retribution Infected Mode, LaSalle appears to be using James Grayson and other former AWOL convicts to report "Anything that looks a bit off" during Operation Overstrike but refuses to tell them anything else about the Chimera. Eventually, Grayson learned about the Gray Tech components and over time, becomes increasingly more curious of these objects. Lasalle would later informed him about the Gray Tech components' capabilities in creating powerful weapons and its importance to SRPA and Specter that could potentially tipped the tide of the Chimeran War in humanity's favor. Furthermore, he forewarn him to be careful when finding Gray Tech because it can be radioactive. LaSalle then proceeded to infect Grayson with a mutated (and possibly better) version of the Chimeran virus, granting Grayson a range of abilities similar to the Sentinels.
LaSalle was also rather interested in the gun towers the Chimera were using to fortify the European-Atlantic coastline, especially in regarding to the energy they used, given to the towers' technology were unlike anything seen among Chimeran technology.
Although LaSalle has been the leader of Specter Team since 1951, Major Richard Blake apparently founded Specter in March 1952 in recovering Gray Tech components across the United States. It is possible that the original Specter Team, directly under LaSalle, was always working in Europe and Blake simply made a second squad to deal with missions specifically in America. However, due to the fact that this information about LaSalle being the leader of Specter in 1951 comes from the Infected Intel of Resistance: Retribution, it should be assumed that it is non-canon (unless proven otherwise).