PINELLAS PARK — A homeless man was arrested Friday morning for sending explicit photos and sexual messages to a 73-year-old woman, Pinellas County Sheriff's Office deputies said. And the same man may be linked to more than 20 similar cases.The woman, a local real estate agent who was not identified, notified officials in June when she began receiving text messages from an unknown person. According to deputies, when she began replying to messages, she received a photo of a man's genitalia and sexual messages in response.An investigation identified 48-year-old Reginald Bernard Nelson of Seminole as the suspected sender. Nelson has also been linked to 21 other similar cases that have been reported to Gulfport Police, Clearwater Police and Treasure Island Police, according to deputies.A common thread in the cases was the fact that all victims were real estate agents. In an interview with deputies, Nelson admitted he sought out realtors in local ads, contacted them and sent explicit messages.He was arrested on a charge of felony cyber stalking, and more charges are pending in the investigation, according to deputies. He is being held at the Pinellas County Jail. His bond was set at $20,000.