INDIANAPOLIS - 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.

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The 77-year-old from the Indianapolis suburb of Zionsville told six adults who believed they were his children that he had donated his own sperm about 50 times starting in the 1970s, a probable cause affidavit said. He had told his patients they were receiving sperm from medical or dental residents or medical students and that no single donor’s sperm was used more than three times.

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 didn’t have a donor sample available,” the affidavit said he told them.

CBS Indianapolis affiliate WTTV reports that, according to court records, Cline said he also “felt that he was helping women because they really wanted a baby.”

“It is very sickening to think he ran his practice up until the time he was about 70,” said an unidentified donor child.

However, 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.

WTTV reports that some of Cline’s biological children simply wish they knew how many siblings Cline produced with his own DNA, but fear that may never come to light.

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. And in 2009, Dr. Ben. D. Ramaley of Greenwich, Connecticut, quickly settled a 2005 lawsuit for using his own sperm.