HOUSTON -- A man who claimed he was a Navy SEAL, married seven women and had three fiancés, was sentenced to 15 years in prison after he changed his plea on a charge of tampering with a government document Wednesday, KPRC Local 2 reported.

Eric Eugene Cooper, 30, was first found guilty Tuesday of forging a signature on one of his ex-wives' car titles. The judge was hearing arguments in the punishment phase Wednesday when Cooper decided to withdraw his not-guilty plea.

"Because the way it played out and we were looking at a 20-year sentence, we thought about it and we didn't want to roll the dice," defense attorney Andrew Williams said.

Cooper's trial began in a Harris County courtroom on Monday. The prosecution lined up several women who Cooper allegedly defrauded to testify.

"All these girls here met Eric Cooper and within a few weeks or days got married to him, then got divorced, got the marriages annulled or whatever they did," Williams said. "What's that got to do with tampering with a government document?"

"Mess with women's lives, mess with their money, mess with their cars, mess with their credit cards," prosecutor Dorian Cotler said.

Cooper has been married seven times and engaged three more times since 1994, prosecutors said.

"The reason why you're allowed to hear all that is because in all of these other cases he had an intent to defraud those victims," Cotler said.

The women testified about how they discovered Cooper was not who he claimed to be.

Jennifer Smith, Cooper's sixth wife, said she broke into his briefcase one night and found several rings.

"At least two bands and maybe three engagement rings," Smith said.

Amber Morgan, 19, said she was engaged to Cooper when she was 18 years old. She provided prosecutors with a Navy uniform that most of the other women said Cooper wore.

"He said that he was a lieutenant in the Navy -- that he had graduated from Annapolis Naval Academy," said Tonya Causey, Cooper's second fiancé.

Prosecutors said Cooper never completed basic training.

Morgan testified on Tuesday that she gave birth to a daughter 10 months ago, fathered by Cooper shortly before he disappeared.

Cooper shed tears in court when Morgan told the court about the child. Cooper did not know about the baby.

Prosecutors said Cooper fathered at least one other child.

Cooper has a lengthy criminal background with convictions for bigamy, credit card abuse and forgery.

Prosecutors said he might be faking his many illnesses, including cancer. Jail records did not indicate that Cooper had the disease.

Cooper must serve at least two years of his 15-year sentence for the felony conviction.