A South Florida man was charged with first-degree murder Wednesday in the killing of a federal agent outside a busy post office.

James Patrick Wonder, 65, was detained without incident after a SWAT team and dozens of officers surrounded a shopping center in this community about 10 miles from Fort Lauderdale, said Pembroke Pines Deputy Police Chief Mike Segarra.

More than 400 law enforcement officers and at least two Blackhawk helicopters had been scouring South Florida for the suspect in the killing of 52-year-old customs agent Donald Pettit.

"I told you we would get him," Segarra announced at a 10 p.m. news conference to a cheering crowd. "Today is a great day."

Click here for photos.

The agent was with his 12-year-old daughter when he was shot during a fight Tuesday morning in a post office's parking lot in nearby Pembroke Pines. Authorities did not immediately know if Wonder, a Miramar resident, had an attorney.

Police received an anonymous tip that led to Wonder's arrest, but Segarra said Pettit's daughter was instrumental in identifying him.

"She's the star," Segarra said. "She is strong. She is something else. With her, and the tip we received, justice was served."

Earlier Wednesday, Pettit's widow, Ileana, pleaded for help in finding her husband's killer. She later thanked the people who turned in more than 500 tips to authorities.

"I can't thank everyone enough," Ileana Pettit said, sobbing during the late-night news conference. "I will sleep better knowing this cold-blooded killer is off the streets."

Click here for a video report from WSVN.com.