Student or Learner
"Powell then decides to subject Prot to regression hypnosis, which works well. Using information gained from these sessions, Powell figures out that Prot is actually one Robert Porter, a man presumed dead since attempting suicide after his wife and daughter were murdered in 1996."
What is the function of "one" in the sentence above? What does it add to the sentence? Is it simply an intensifier?
Not a teacher, but I'll try to answer this. Feel free to correct me if i'm wrong.
Yes it is an intensifier. I think it's more stylistic than anything, it functions sort of as a definite article, but it serves to highlight that it is, in fact, Robert Porter.
Omitting it entirely would be more common and wouldn't alter the meaning in any way.