Cup Foods store employee Christopher Martin speaks as a witness about George Floyd paying with counterfeit $20 bills, as a…
Christopher Martin testifies about George Floyd paying with counterfeit $20 bills, as a store surveillance video plays on a screen, during the trial of Derek Chauvin, in Minneapolis, Minnesota, March 31, 2021, in this courtroom sketch from a video feed.

The trial of Derek Chauvin, the police officer charged in the death of George Floyd, continued Wednesday in the U.S. state of Minnesota with testimony from the convenience store cashier who sold cigarettes to Floyd moments before his deadly encounter with Chauvin.

Christopher Martin testified that he knowingly accepted a fake $20 bill from Floyd for the cigarettes even though the money would be subtracted from his paycheck in accordance with store policy.

The 19-year-old said after second-guessing his decision, he informed the store manager who told him to go outside and ask Floyd to return to the store.

"If I would've just not (taken) the bill, this could've been avoided," Martin said.

A memorial at the place where George Floyd died is seen while the city of Minneapolis enters its third day of the trial of Derek Chauvin, in Minneapolis, Minnesota, March 31, 2021.

Echoing sentiments from other onlookers, Martin said he felt "disbelief and guilt," as he stood on the curb watching Floyd's arrest.

Martin was among several people who have testified about their frustration and anger as they witnessed Chauvin kneeling on Floyd's neck outside a convenience store last May.

Chauvin kneeled on the back of Floyd's neck for 9 minutes and 29 seconds as Floyd cried repeatedly that he could not breath.

Chauvin, who is white, was fired by the city's police department the day after Floyd, an African American, died in custody.

The officer is facing charges of murder and manslaughter and has pleaded not guilty.

Chauvin's defense lawyers have argued he was following his training and that other factors such as heart disease and drug use caused Floyd to die.

Floyd's death and a video from the scene that was shared widely on social media and news programs sparked protests in numerous areas across the United States and other parts of the world against police brutality and systemic racism.

The city of Minneapolis recently agreed to pay Floyd's relatives $27 million in damages to settle their claims of abuse in the case.