Benedict Arnold: Did the Americans Know About His Proposed Treachery Before His Defection?

Upon learning of the defection one of his favorite generals, Benedict Arnold, General George Washington openly wept in shock.

But Arnold's defection should not have surprised Washington. According to the historical record, the evidence had been there since Arnold, who'd pleaded with Washington for a post at West Point, first assumed command of this important area of defense.   In a pointed letter, Benjamin Talmadge, head of the Culper spy ring, chastised the would-be-traitor for the forts'  general state of disrepair, warning him of the opportunity its vulnerabilities presented to the British, who long had coveted this key spot on the Hudson,, which, if captured, would enable the Empire to sever the connection among many of the provinces. 

Surely, Talmadge must have wondered why Arnold allowed West Point to lapse. Did it not cross the spy's mind that the disgruntled general might be purposely undermining the defenses? Why did he not tell Washington, his immediate supervisor, about the state of West Point?