A key witness for prosecution in the murder case of a metro doctor "impeached himself with false testimony" last week, according to court authorities.

The testimony last week of Oklahoma Highway Patrol Maj. Ronnie Hampton in the murder trial of Dr. Bryan Perry prompted special instructions to the jury Monday morning:

"Evidence has been presented that on some prior occasion, Major Hampton made a statement inconsistent with his testimony in the case. This evidence is called impeachment evidence and it is offered to show that the witness's testimony is not believable or truthful. If you find that a statement was made, you may consider this impeachment evidence in determining what weight and credit to give the testimony of that witness. You may not consider this impeachment evidence as proof of innocence or guilt. You may consider this impeachment evidence only to the extent that you determine it affects the believability of the witness, if at all."

Perry, 49, is accused of driving drunk on Interstate 35 and hitting Nicholas Rappa, 31, on his motorcycle, killing him. He had been charged with second-degree murder, aggravated driving under the influence, leaving the scene of a deadly accident and obstructing an officer. A lesser charge of manslaughter has now been included for the jury to consider.

Oklahoma County prosecutors and defense attorneys rested their cases Friday after a week of testimony.

Hampton had testified that Perry was driving about 100 mph when he slammed into the back of Rappa’s motorcycle. The witness said the crime scene on the interstate stretched for more than a mile based on the debris field, where Rappa’s body landed and the ditch Perry ran to.

After the state rested, Perry’s defense team called their one witness. The former law officer, now a private accident reconstruction expert, testified that Perry was not speeding and most likely could not see Rappa’s dark motorcycle.

“It’s coming out through the testimony that there’s no reflective materials on the back of the motorcycle,” said Scott Adams, defense attorney. ‘’That the rain coming down, the dark conditions, everything that was going on -- I think it’s pretty evident that no one could have avoided this accident.”

This is a developing story.