FAIRFIELD — A Bridgeport man police say robbed someone at gunpoint in November was arrested Monday.

Johnny Diaz, held on $75,000 bond, was charged with first-degree robbery and conspiracy to commit first-degree robbery.

According to police, Diaz, 21, made arrangements with the victim, via the phone app Offer Up, to meet on Browns Lane on Nov. 15 to sell the victim an iPhone. However, the report states Diaz and another man approached the victim, pointed a gun at him and threatened him, and then took his money, his cellphone and his car keys. The victim went to a nearby house to call the police.

The investigation, which included a search warrant issued to Offer Up and a review of Diaz’ Facebook page, led to the arrest.

Diaz, who lives on Platt Street in Bridgeport, was given a court date at state Superior Court in Bridgeport on Wednesday.