FRAMINGHAM, Mass. (AP) — Col. Timothy Alben thought it was likely another dead end when he first heard about a 911 call from a man who thought someone was hiding in his boat following a fruitless daylong manhunt for a suspect in the Boston Marathon bombings.

But not long after Alben, the leader of the state police, and other law enforcement officials appeared crestfallen at a news conference, their disappointment turned to jubilation.

The man in the boat turned out to be Dzhokhar Tsarnaev, the 19-year-old now charged in the bombings.

During an interview Thursday with The Associated Press, Alben recalled his joy when he heard the words ‘‘suspect in custody’’ come over the police radio.

‘‘There was elation, certainly celebration and a great deal of relief,’’ he said.

Tsarnaev’s capture came following a week that started out for Alben as a typical Marathon Monday. He started his day in Hopkinton, the start of the marathon and where state police begin to provide security that stretches along the 26-mile marathon route.

‘‘It was just a beautiful day. I think everybody was just happy to be there,’’ he recalled.

A few hours later, Alben left to head to his home in western Massachusetts, when he got a call from Boston police Commissioner Ed Davis.

‘‘He said: ‘I need your SWAT teams right away. I've got a few explosions,'’’ Alben said.

At first, Alben thought it may have been manhole explosions. The city had had a spate of manhole cover explosions last year.

He soon learned it was much more serious, an event with mass casualties that was quickly described as a terrorist attack. Three people were killed and more than 260 were injured, including many who lost legs in the two explosions.

The next few days were a blur, with little sleep, as the FBI and police frantically searched through footage from surveillance videos and eventually discovered images of Tsarnaev and his older brother, Tamerlan, near the finish line. Within hours after the FBI released the video and asked for the public’s help to identify the suspects, Alben received calls about an MIT police officer being shot and killed in Cambridge and a wild chase into Watertown that had the suspects throwing pipe bombs and other explosives at police.

Tamerlan Tsarnaev died following a police shootout that ended as police tackled him and his brother ran over him during a chaotic escape. The daylong manhunt followed, with police capturing Dzhokhar in the Watertown boat late on April 19.

Alben credits cooperation between state police, Boston police, the FBI, Watertown police, Cambridge police and others with Tsarnaev’s capture and the ability to avoid further bloodshed.