A retired Indianapolis fertility doctor used his own sperm at least 50 times instead of donated sperm that his patients were expecting, impregnating at least eight women decades ago, court documents say.

Dr. Donald Cline, 77, pleaded not guilty Monday to two felony obstruction of justice charges for misleading authorities who were investigating complaints from two of the now-adult children against him.

Cline is accused of being the biological father of at least eight people, the youngest of which would be about 30. The accusations against him were first reported by WXIN-TV in May.

One of the adult children took a saliva-based DNA test through a private personal genomics company and found that she was related to at least eight other people in its database, the affidavit said. Meanwhile, two others also investigated their ancestry through DNA tests and learned their mothers both were patients of Cline and that they were related to 70 relatives of Cline, it said.

Cline "said he used his own sperm whenever he did not have a donor sample available," the affidavit said he told them. But when the state began investigating complaints, Cline denied having done so.

"I can emphatically say that at no time did I ever use my own sample for insemination," he said in a letter to the Indiana Attorney General's Office. Cline retired from his practice at Reproductive Endocrinology Associates in Indianapolis in 2009. Cline's attorney, Tracy Betz, released a statement saying he is not accused of hiding documents, influencing witnesses or otherwise not cooperating with the attorney general's investigation. Cline was released on his own recognizance.

The most notorious fertility doctor to secretly use his own sperm was Cecil Jacobson, who may have fathered as many as 70 children from 1976 to 1998 in Vienna, Virginia. In 2009, Dr. Ben. D. Ramaley of Greenwich, Connecticut, quickly settled a 2005 lawsuit for using his own sperm.