A man who was found dead early Monday on railroad tracks in Catasauqua was fleeing from a borough police officer, and was hit with a stun gun before falling over a bridge railing, prosecutors said.

Lehigh County District Attorney Jim Martin said in a news release Tuesday he was continuing to investigate the death of Kevin Duffy, of Whitehall Township.

Martin said, however, that he viewed video from the officer's patrol vehicle dashboard camera, and it appeared that Duffy voluntarily went over the bridge railing.

Catasauqua officer Donald Stratton was on patrol when he saw Duffy in a 1998 black Ford Explorer fail to use his turn signal at Third and Bridge streets, according to the news release.

Stratton put on his lights, but Duffy turned right and continued to Front and Pine streets, where he stopped at a red traffic light but then turned right on Pine Street headed east, prosecutors said.

Duffy pulled over at Pine and Railroad streets, then pulled away and stopped at Second and Pine streets.

The SUV took off, and stopped on the Pine Street bridge, where Duffy got out and started running away, authorities said.

Stratton chased Duffy, drew his stun gun and yelled for Duffy to stop before firing the stun gun, prosecutors said. The stun gun probes appeared to hit Duffy in the back, but he kept moving, eventually throwing his leg over the ledge of the bridge and rolling off, authorities said.

Duffy fell about 32 feet, onto Norfolk Southern railroad tracks. Martin said the preliminary cause of death is blunt force trauma to the head and chest. An autopsy also showed the stun gun probes failed to penetrate Duffy's skin.

"I have viewed a video taken from Officer Stratton's patrol vehicle dashboard camera, and it appears that Mr. Duffy went over the rail of the bridge completely voluntarily and without any action on the part of Officer Stratton," Martin said in a news release.

Sarah Cassi may be reached at scassi@lehighvalleylive.com. Follow her on Twitter@SarahCassi. Find Lehigh County news on Facebook.