Police: Detail cop scared off pipe-bomb robber, accomplice on first attempt to hold up Canal Street bank

Takedown. Photo by Kristen RomanelliWilliam DeVincenzi and Thomas Sawtelle of East Boston, arrested in dramatic fashion on Wednesday morning outside a Bank of America branch, originally wanted to rob the bank on Monday, according to a report by a member of the FBI's Violent Crimes Task Force - which had the two under surveillance the whole time.

But when they saw a detail cop standing right in front of the bank, they turned around and took the T back to Eastie, the report says.

In an affidavit filed in US District Court, task force member and Somerville Police Det. John Oliveira said investigators watched DeVincenzi - now also charged with two successful bank robberies with an "inert" pipe bomb last week - leave his home at 873 Saratoga St. on Monday and meet up with Sawtelle. They then walked over to the Walgreens on Meridian Street. DeVincenzi - who has a record that includes manslaughter, drug dealing and armed robbery - went into the store and left carrying a green accordion-style envelope.

Oliveira, who writes investigators were tipped off by an agent at Alcohol, Tobacco and Firearms to watch DeVincenzi, continues the two then took the Blue Line into town, eventually transferring to another train to Haymarket, where they exited and walked to Friend Street. DeVincenzi, he writes, handed a cup of coffee to Sawtelle and put on a windbreaker, a pair of dark sunglasses and a pair of dark gloves. DeVincenzi took something out of his waistband and put it in the accordion envelope.

"As he did so, I was able to observe that the items had black wires," Oliviera writes. And then the two walked to Friend and Valenti, a few yards away from the Bank of America branch at 104 Canal St.:

Both individuals came to an abrupt stop as they observed a Boston police officer on a paid detail at that location. Both turned around and headed back in the same direction from which they came. At that time, DeVincenzi removed his hat, sunglasses, outer jacket and gloves. He then began removing what was later identified as clear tape with gauze which was on right hand. Both individuals headed into the T station and surveillance concluded at that point.

Surveillance continued. Around 8:20 a.m. on Wednesday, the affidavit says, DeVincenzi left his home again, wearing the same red-and-black flannel jacket he wore Monday, and carrying a windbreaker. He met Sawtelle at the Maverick T stop. They were observed getting out of the T at Haymarket. They walked over to Friend Street, where DeVincenzi again put on the windbreaker, a black knit cap and dark gloves. Holding a green accordion folder, they walked over to Friend and Valentine, about 20 yards from the bank branch.

And then they were swarmed by armor-wearing FBI agents and State Police. Oliviera concludes by saying both admitted to the attempted holdup and that DeVincenzi also acknowledged the holdups last week.

• Complete affidavit

Innocent, etc.