Why was Booth admitted into the presidential box?

[RJNorton]

Another close witness was Captain Theodore McGowan who was seated on the right side of the dress circle. Here is his account of what took place:

"I was present at Ford’s Theatre on the night of the assassination. I was sitting in the aisle leading by the wall toward the door of the President’s box, when a man came and disturbed me in my seat, causing me to push my chair forward to permit him to pass; he stopped about three feet from where I was sitting, and leisurely took a survey of the house. I looked at him because he happened to be in my line of sight. He took a small pack of visiting-cards, selecting one and replacing the others, stood a second, perhaps, with it in his hand, and then showed it to the President's messenger, who was sitting just below him. Whether the messenger took the card into the box, or, after looking at it, allowed him to go in, I do not know; but in a moment or two more, I saw him go through the door of the lobby leading to the box and close the door."