A Justin Bieber fan was arrested at the singer's Beverly Hills home Monday after cops say she wandered onto the property looking for the singer ... for the third time this week.
Law enforcement sources tell TMZ cops got a call to the home around 7:30 PM ... we're told Justin's security detained the woman until officers arrived.
Our sources say the woman -- in her 40's -- showed up at the home two other times in the last week and was warned by security to stay away. We're told she made it on the property but did not make it inside the home.
Justin was home during the incident, but did not make contact with the woman.
She was booked for trespassing.