The unidentified man was detained for an undisclosed medical condition but was not arrested, E! News reports. Multiple sources told E! that the man seemed unstable and was even heard yelling Swift's name.
It's not clear if the pop star was home at the time.
As the investigation continues, Swift's spokesperson took the media to task, telling E! "This is why it's irresponsible for the media to publish the addresses or recent real estate transactions of celebrities. This, or potentially worse, is the end result.