The three boys who allegedly shot dead Australian baseballer Chris Lane are expected to appear in an Oklahoma court.

Prosecutors will announce if the boys - aged 15, 16 and 17 - will be charged with first degree murder and be tried as adults.

If so, the boys could be sentenced to life in jail if convicted.

The arraignment at the Stephens County Courthouse in Duncan is expected to be held about 1.30pm local time (0430 Wednesday AEST).

The random drive-by shooting has shocked locals.

Police allege the 17-year-old has confessed to being the driver and explained they randomly targeted Mr Lane because they were bored.

Mr Lane, 22, who had a scholarship at an Oklahoma college to play baseball and major in finance, was jogging on a Duncan street on Friday when he was shot in the back.

Richard Rhodes, a builder who heard the shot, told AAP he performed CPR on Mr Lane but was unable to revive him.

Mr Lane's longtime American girlfriend, Sarah Harper, has described his killers as "evil".