Daniel Penny's martial arts instructor from the Marine Corps took the stand Thursday for day six of witness testimony in Penny's trial in the chokehold death of Jordan Neely.

A subway commuter who helped an ex-Marine restrain an agitated man aboard a Manhattan subway last year testified that he tried to convince the veteran to loosen his grip around the man’s neck.

The man seen on video helping Daniel Penny restrain Jordan Neely on board the subway last year took the stand Tuesday on day five of witness testimony in Penny's trial.

A Marine veteran and martial arts instructor who served alongside New York City subway chokehold suspect Daniel Penny takes the witness stand.

Joseph Caballer, a nine-year veteran of the corps who trained troops in self-defense, told the jury Daniel Penny's elbow and hand were "not in the correct position" for a proper figure-four chokehold and he could have been cutting off Jordan Neely's windpipe.

Daniel Penny's martial arts instructor from the Marine Corps took the stand Thursday for day six of witness testimony in Penny's trial. The Marine veteran is accused in the chokehold death of Jordan Neely on the subway last year.