A 51-year-old man wanted in the the sexual assaults of at least three women at gunpoint last week in the West Philadelphia's Parkside section has surrendered to police.

Police Commissioner Richard Ross said Thursday morning Robert Johnson, accompanied by his brother, turned himself in to Southwest Detectives at 55th and Pine streets after investigators identified Johnson as a suspect and released his photograph.

Police recovered a weapon after executing a search warrant at Johnson's home on the 4100 block of Leidy Street before he surrendered, police said.

Police identified Johnson, a convicted sex offender,  as a suspect Wednesday night.

A call from a tipster proved helpful to leading investigators to Johnson, Ross said.

Capt. Mark Burgmann of the Special Victims Unit and investigators were concerned the assailant would strike again.

"It was scary when we saw that," he said, referring to what he called the "absolutely brazen" attacks.

Police gave these accounts of  last week's attacks.

On July 17 at Belmont and Parkside Avenues about 5:45 a.m., a man approached a woman and threatened her with a gun. He forced the woman to walk into Fairmount Park, where he sexually assaulted her and took her Beats headphones and her iPhone.

On July 19 about 4:20 a.m. at a gas station at 4800 W. Girard Ave., the suspect approached a woman, who was pumping gas, and threatened her with a gun. He forced her and another woman in the car to travel to an unknown location, where he sexually assaulted both women and then fled with $420 cash.

Police said Johnson also was a suspect in a sex assault during a home invasion last month.

Staff writer Joseph A. Gambardello contributed to this article.