Fresh clues to how and why Australian baseballer Chris Lane was shot and left to die in a US street are expected to be revealed in an Oklahoma court.

The preliminary hearing for two of the three teenagers accused of Lane’s drive-by murder, Chancey Luna and Michael Jones, will continue in the southern Oklahoma city of Duncan on Wednesday (Thursday AEDT).

The third and youngest teenager charged with Mr Lane’s death, James Edwards, 16, has become a prosecution witness and is hoping to have a first-degree murder count downgraded to an accessory charge.

The hearing came to a dramatic halt on February 6 when a friend of the trio, KJwan Martin, refused to testify without talking to a lawyer first.

Martin, 18, returns to the stand on Wednesday.

Edwards, who was 15 at the time of the shooting, testified he smoked marijuana with Martin a few hours after Mr Lane was shot.

Luna, 16, and Jones, 18, face life in prison if convicted of Mr Lane’s first-degree murder.

Judge Jerry Herberger will decide at the end of the hearing if there is enough evidence for Luna and Jones to stand trial.

Mr Lane, 22, had a baseball scholarship at Oklahoma’s East Central University and was staying at his girlfriend Sarah Harper’s home in Duncan on August 16 last year when he went out for a jog and was shot.

Police said Jones told them Mr Lane was shot because the teens were bored.

Edwards testified Jones’ Ford Focus unexpectedly veered sharply, then Luna’s .22 revolver fired, hitting Mr Lane in the back.

Edwards also testified he later heard Luna say he thought they were blanks, not bullets in the gun, buoying defence lawyers’ theory the shooting was not premeditated.