SAUGUS ? Saugus Police are asking the public for help finding a man who allegedly sexually assaulted a woman at knifepoint Tuesday night.?The suspect told the victim that he had a knife and ordered her not to scream,” Saugus Police said in a press release.Police said a woman told police she had been out running with her dog on Nason Road at around 10:30 p.m. Tuesday when she heard fast footsteps approaching from behind her. The alleged victim reported a man then grabbed her by the hair and pushed her into a tree. The man then allegedly grabbed the woman’s chest and genitals and hit her in the face. The alleged victim’s dog started barking, causing other neighborhood dogs to bark and possibly spooking the suspect, who ran away, police said.The alleged victim described the suspect as tall, thin and wearing a long-sleeved red shirt, dark pants (possibly jeans) and clean white sneakers. He also was wearing cologne, according to police.Saugus Police and a Massachusetts State Police K-9 unit were unable to locate the suspect.The investigation is active and ongoing. Anyone who may have been in the area or who may have any information is asked to call Saugus Police at 781-941-1199 or the Anonymous Tip Line at 781-231-4307.