ESCONDIDO–Las Vegas police arrested a 38 year-old San Marcos man in connection with the murder of his girlfriend found shot in her vehicle on the on-ramp to northbound Interstate 15 in Escondido Monday. A Las Vegas police officer Tuesday conducted a traffic enforcement stop on a vehicle occupied by the suspect, identified as Edward Long. The police officer arrested Long on murder charges in connection with the death of 38 year-old Elizabeth Perez. Long is currently in a jail in Las Vegas. He has waived extradition, and arrangements are currently underway to return Long to San Diego county to face charges. Escondido police homicide detectives say Long was a person of interest in the death of Perez, a resident of Fontana. Detectives served a search warrant at Long’s residence in San Marcos where several items were seized. On Monday, CHP, Escondido police, and Escondido fire personnel responded to a report of an unresponsive female in a vehicle on the on-ramp to northbound I-15 from El Norte Parkway. Paramedics determined that the female was deceased. She had a head injury and was seated in driver side of the vehicle. The front driver and passenger side windows of the black Mercury Sable were shattered. The investigation of the incident is ongoing.