In the greater than 50 years since a bomb ripped by a arithmetic middle on the University of Wisconsin, killing a graduate scholar and injuring a number of others in what was thought-about an assault protesting the Vietnam War, the F.B.I. has acquired a whole lot of suggestions in regards to the whereabouts of one of many suspects, Leo F. Burt.

Just weeks after the assault on Aug. 24, 1970, a waitress in Cleveland was convinced that she had seen him. Years later, one other tipster thought he had noticed Mr. Burt at a homeless shelter in Denver. One man mentioned he had seen the fugitive working at a resort in Costa Rica. But Mr. Burt was by no means discovered.

Last week, in an try and develop new leads, the Federal Bureau of Investigation launched new images of what Mr. Burt may seem like as we speak, aged to round 75 years outdated.

Gone are his grin and thick brown hair from an earlier {photograph}. A frowning Mr. Burt is now depicted graying and balding and, in response to the F.B.I.’s remarks beneath the picture, might have a mustache, beard or lengthy hair. In one of many photographs, he wears the identical wire-framed spherical glasses that he wore as a younger man. He stays needed for sabotage, destruction of presidency property and conspiracy, and “should be considered armed and dangerous,” the F.B.I. mentioned.

Mr. Burt, a University of Wisconsin scholar in his 20s on the time of the assault, was amongst 4 males who the authorities say plotted to bomb the arithmetic middle within the early hours of Aug. 24, committing the biggest act of home terrorism on the time.

The 4 males are mentioned to have detonated a stolen truck containing fertilizer and gas oil close to Sterling Hall, the constructing that housed the arithmetic middle, which was affiliated with the U.S. Army. The blast and hearth killed Robert Fassnacht, a 33-year-old physics researcher, and injured 5 others. Investigators on the time mentioned the explosion prompted round $6 million in injury.

After the assault, the authorities mentioned the bombers fled to Canada. Three of the suspects, Karleton and Dwight Armstrong, who had been brothers, and David Sylvan Fine, had been ultimately captured.

Karleton Armstrong, a former scholar on the University of Wisconsin, was arrested in 1972 close to Toronto and extradited to Madison, Wis., the place he pleaded responsible to arson and second-degree homicide and was sentenced to as much as 23 years jail.

Mr. Fine, who, like Mr. Burt, was a scholar on the college, was arrested in 1976. He pleaded responsible and acquired a seven-year sentence. He was paroled in 1979.

Dwight Armstrong, who was not a scholar, remained on the run till 1977, when he was arrested and pleaded no contest to a state cost of second-degree homicide and responsible to federal fees together with conspiracy. He was sentenced to seven years on the state fees and 7 on the federal fees, to be served concurrently. He was paroled in 1980 and died in 2010.

The Milwaukee subject workplace of the F.B.I. said it had released the new images to coincide with the 53rd anniversary of the bombing and was providing a reward of as much as $150,000 for info resulting in Mr. Burt’s arrest. Federal investigators mentioned he was seen leaving the college in a light-colored Chevrolet Corvair.

Mr. Burt was born in Darby, Pa., and, on the time of the bombing, rowed on the college’s varsity workforce and wrote about sports activities for the coed newspaper. But associates mentioned he had “changed into an avid follower and reporter of the radical movement,” in response to a 1970 article in The New York Times.

The police mentioned that two minutes earlier than the bombing, which came about at about 3:45 a.m., they acquired an nameless name. “Hey, pig, there’s a bomb in the math research center,” the caller mentioned, in response to news reports on the time. The blast tore aside the six-story constructing, destroying most of its contents, together with a $1.5 million pc, and shattering home windows as much as 10 blocks away from the campus.

In the greater than 5 a long time since, the F.B.I. has acquired a whole lot of recommendations on Mr. Burt.

“But the fugitive has somehow managed to elude capture, leading some to believe he is dead,” the company mentioned in a news release in 2010. At the time, the company additionally issued photographs of what Mr. Burt may need seemed like at that time.