SAN DIEGO -- He was just awarded more than $750,000 for wrongful imprisonment, and now Kenneth Marsh is seeking $50 million in a civil lawsuit.

The new lawsuit claims there was conspiracy to blame 2-year-old Phillip Buell's death on Marsh -- a plan to cover up medical malpractice, but the man who prosecuted Marsh for Buell's murder says important facts are being ignored.

It's been nearly 23 years since Marsh was convicted of killing his girlfriend's son and more than a year since Marsh's release from prison.

Marsh fought for his freedom for more than two decades and the child's mother was at his side the entire way.

They claimed 2-year-old Buell fell on a fireplace hearth and a broken ashtray.

The 1983 conviction in Buell's death was finally set aside in August 2004, and Marsh became an instant spokesman for the wrongly convicted.

"Never give up hope and never take anything for granted because it could be taken away in a heartbeat," said Marsh.

But the man who prosecuted Marsh is troubled by his status as a hero for freedom.

"The explanation given by Mr. Marsh was not true," said former Deputy District Attorney Jay Coulter.

Coulter said prosecutors in the appeals process ignored key physical evidence.

Buell had multiple cuts and one gash in his neck 1 1/2 inches deep and two inches long.

There was no blood on the fireplace hearth where Marsh said Buell fell.

There was also no blood on the glass shards from the broken ashtray that allegedly cut him.

Marsh's attorney says it's not significant.

"The cuts that were scrapes....occured when Buell fell on the hearth," said Marsh's attorney, Donnie Cox.

In fact, Buell's death was officially blamed on brain hemoraging.

Attorneys argued over the causes of that hemoraging, but Coulter said there has never been a good explanation for the cuts and the absence of blood.

"Until someone can explain that to me, I have trouble accepting the fact that Mr. Marsh is innocent of this crime," said Coulter.

Coulter says he was silent until now because Marsh did spend 21 years in prison, but says Marsh's celebrity status and the multiple lawsuits filed caused him to speak up.

As far as the latest lawsuit goes, attorneys for Children's Hospital are asking the court to dismiss the suit, calling it "far- fetched."