TAMPA, Fla. — After enduring almost two months of fear, a Tampa neighborhood breathed a sigh of relief Wednesday after authorities announced the arrest of a suspected serial killer, a recent college graduate who gave himself away after asking a co-worker to hold a bag containing a handgun.

Howell Emanuel Donaldson, who was working as crew chief at a McDonald’s, was charged with four counts of first-degree murder in a string of shootings that targeted people near bus stops.

“We had a community that was on edge,” Mayor Bob Buckhorn said. “Today the light shines. The darkness is over. This community begins the healing process.”

Neighbors of the 24-year-old – who lived in a different area of Tampa than where the slayings took place – said they recently saw him playing basketball with his younger brother in the driveway of the family’s suburban home. Now they’re watching news of him on television, puzzled as to how a kid who went to college in New York on a basketball scholarship ended up behind bars. “He’s very nice. He waves, very polite,” said neighbor Kelly Fabian, who said she walked Donaldson to school when he was younger. “Quiet kid. It’s a shocker.”

Arrest records did not list an attorney for Donaldson, and the police chief said he did not know if the suspect had a lawyer yet. He’s scheduled to make a first court appearance Thursday in Hillsborough County.

The arrest, which happened Tuesday night, brought immense relief to the anxious neighborhood of Seminole Heights, which had stopped many outdoor activities since the first death on Oct. 9. Two more fatal shootings happened in the weeks that followed, and residents were so scared that police escorted children while they trick-or-treated. The fourth killing happened earlier this month.The crack in the case came Tuesday when Donaldson brought a bag holding a loaded Glock .40-caliber handgun to McDonald’s and asked a co-worker to hold it while he went across the street, authorities said.

Restaurant workers thought Donaldson’s request was odd. When he left, they reported the gun to a police officer who was doing paperwork there. When he returned to the restaurant, officers were waiting.

In addition to matching shell casings found at the shootings, authorities said location data from Donaldson’s cellphone put him at the scene of at least three of the killings.

“The gun is what we needed,” Police Chief Brian Dugan said at a news conference.