Police in San Antonio said Monday that they had arrested a man wanted in the ambush killing of an officer fatally shot a day earlier, reports the Washington Post.

San Antonio Police Chief William McManus said during a briefing that a SWAT team had arrested Otis Tyrone McCain. According to McManus, McCain was arrested without incident following a sprawling manhunt sparked by the killing of Detective Benjamin Marconi, who was slain while writing a traffic ticket in front of police headquarters on Sunday morning.

McCain is “the person we believe is responsible for the cold and calcuated murder of Detective Marconi,” McManus said during a briefing late Monday afternoon. “We are relieved to have taken him into custody without a further loss of life.”

Police said they still do not know a motive for Marconi’s death, and McManus declined to say what led authorities to the 31-year-old McCain. During a briefing earlier in the day, McManus said police did not believe the officer’s death was tied to another attack in St. Louis that occurred hours later on Sunday.

“I will say that it is certainly a coincidence, but we’re not going to venture to say that it’s connected,” McManus said.

During the briefing after McCain was arrested, McManus said that officers still remain wary in the face of other threats facing law enforcement.

“The fact that he’s been taken into custody, that does not negate the fact that there are people out there who are still targeting police officers,” McManus said. “So our officers will always be vigilant and on guard for that.”

Police also said Monday that the suspected attacker had briefly visited the department’s headquarters not long before the shooting, although McManus said investigators were not sure what prompted this visit.