SACRAMENTO (CBS13) — Joseph DeAngelo is facing two murder charges in Sacramento County for the 1978 deaths of Bryan and Katie Maggiore.

The alleged East Area Rapist is also accused of more than 50 rapes across the state. But will DeAngelo even be charged with those sex assaults?

READ MORE: Truck Stuffed With Recyclables Catches Fire, Prompts Closure On State Route 99 Near Elk Grove

“It comes as a surprise to many in the public, you know, when you catch the bad guy and you can’t prosecute him for crimes that may have occurred because they happened a long time ago,” said John Myers, a law professor at the McGeorge School of Law.

Twelve murders and more than 50 rapes, all crimes investigators say have one culprit: the East Area Rapist. But there’s one big impediment to prosecuting all of those crimes: a statute of limitations.

“You only have a certain number of years after a crime occurs during which there can be a prosecution,” Myers said.

Yolo County District Attorney’s Office is investigating three sexual assaults in Davis from 1978. And back then, the statute of limitations was only three years. California law changed in 2016 eliminating the statute of limitations for rapes committed after 2016, but it’s not retroactive.

“The statute of limitations has clearly expired decades ago which makes it very unlikely that any of these crimes could be prosecuted today,” Myers said.

But is there any way around the statute?

READ MORE: California To Vote On Adding Constitutional Right To Abortion In November Midterm Election

“They’re going to try to piggyback some punishment on top of the old crime,” Myers said.

In other words, prosecutors could try to prove that DeAngelo had a weapon while committing the sexual assaults.

“I think the odds of that succeeding are very slim,” Myers said.

Myers says even if the statute of limitations wasn’t a factor, proving a rape case after 40 years is nearly impossible.

“Witnesses have died, they’ve moved away, memory fades, evidence may have been destroyed, documents are lost!” he explained.

In his opinion, the best option for the prosecutors is to pursue their strongest murder case against the 72-year-old.

“They will probably get a conviction and then he’ll be in jail for the rest of his life,” Myers said.

MORE NEWS: 1 Building Burned In Vegetation Fire Near Rancho Cordova

Yolo County District Attorney Jeff Reisig said “we are actively working on the cases. Some options may exist but we need to finish the investigation. We are not surrendering the issue.”