HOUSTON --A man is accused of bilking more than $80,000 from an elderly Houston woman in an alleged Ponzi scheme. Robbie Dale Walker, of Dripping Springs, was arrested Wednesday for theft over $200,000, a first degree felony. Authorities say the investigation began in early April 2011 after Walker met with the 93-year-old victim. She was reportedly approached by Walker for an investment with RD Walker Resources, Inc., a firm he identified as a gas and oil exploration company. The victim said she had known Walker for some time and trusted him. Authorities say there was ultimately no return on the investment and Walker continued to request additional funds from the victim to assist in "development" and a return on her investment. Details from the investigation led detectives to believe this was a Ponzi scheme. Walker was released from the Hays County Jail after posting a $10,000 bond. If convicted, the punishment ranges from 5 to 99 years and a fine of up to $10,000. Authorities say the possibility exists that there are other victims from the Hays County, Austin and Houston areas involved in this scam through Robbie Walker or his company RD Walker Resources, Inc. who have not yet been identified. If you believe you have been a victim in the manner described, please contact Hays County Sheriffs Office at 512-393-7896 to file a report.