Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
infiltrate (v.)
can combine with two groups of prepositions. If the locution designates the place, group, or other entity that is being infiltrated, the prepositions are into (Our agents hope to infiltrate into their intelligence-gathering organization) and sometimes to (Our pioneer companies infiltrated to the enemy supply dumps on the other bank). If the locution designates who or what is doing the infiltrating, then with or by are the prepositions: Their intelligence agency was infiltrated at several levels with [by] our agents. Other prepositions also occur occasionally, including among, from, through, toward, and within: Our spies infiltrated among [through, within] the crowd. Our scouts were told to infiltrate from [toward] the ravine. Infiltrate can also be transitive and take a direct object, without a preposition: We infiltrated their perimeter line.
