A man arrested by US police for the assassination of a lawnmower was a communist sympathiser who acted alone, the FBI said last night.

Keith Walendowski killed the Black & Decker Lawn Hog with two shots fired from a 6.5mm Mannlicher-Carcano rifle from the upstairs bedroom window of his Milwaukee home, agents said.

They claim he developed a hatred of American mowers after defecting to the Soviet Union, which he expected to be a lawnmower-based utopia.

Special agent Carl Booker said: "He was shocked to discover how backward Russian grass-cutting was. Most of their mowers were still side discharge with no rear bag or mulching facility.

"When he came back he brought his Russian mower along. He was always bragging about it, but he knew his grass was a mess. Last week he got drunk and took a swing at a rotovator."

Booker said Walendowski's first shot went straight through the Lawn Hog before entering a Bosch electric chainsaw, while the second and fatal shot entered the mower from the rear.

However, eye witnesses claimed there were six shots from two directions, while experts say injuries to the chainsaw prove at least one other gunman was involved.

Ballistics expert Wayne Hayes said: "Are we expected to believe one bullet could pass through the mower, stop in mid-air, turn 90 degrees, and then continue through the chainsaw and emerge on the grass without so much as a scratch?

"Also, the fatal shot sends the Lawn Hog back and to the left, exactly what you would expect if the shot came from the front-right.

"If the fatal shot came from the front then you have to conclude there was second rifleman, and if there was a second rifleman there had to be a conspiracy, one which we believe involves Joe Pesci and Tommy Lee Jones."

Hayes added: "Back and to the left. Back and to the left. Back and to the left."