Watch CBSN Live

Expert: Motive in Yale Murder Not Needed

With word on evidence pointing to the suspect arrested in the murder of Yale graduate student Annie Le - blood traces, a text message, a security access card showing he was with the victim - the investigators' case against Raymond Clark III appears strong.

But is physical evidence sufficient for prosecutors to obtain a guilty verdict if they do not have a motive for the crime?

CBS News legal analyst Lisa Bloom said, "Absolutely."

Clark, 24, is being held in a high security Connecticut prison on $3 million bond.

One law enforcement source told CBS News correspondent Randall Pinkston that . Clark is described by lab researchers as having a bad temper and had been known to explode at them.

Investigators have been questioning a number of people, including other employees at the lab where Clark and Le worked. [Clark's brother-in-law and sister also worked in the same building.]

Appearing on "The Early Show" Friday, Bloom said that prosecutors do not have to prove motive.

"It's not an element of murder or any homicide crime," she said. "Sure, they'd like to have it, because a jury is always going to be curious as to what the motive is. But when there's a mountain of physical evidence which sounds like what we're gathering here now, they certainly don't need to have motive."

More on the Annie Le investigation at
Portrait Emerges of Yale Murder Suspect
Yale Student Suffocated, Coroner Finds
"The Early Show:" Yale 'Unnerved' By Murder
Yale Student's Slaying an Inside Job?
Cops: Yale Student Killing Not Random Act

Bloom suggested that there could be many reasons behind the killing. "It could have simply been that this defendant flew into a rage over a workplace dispute," she told "Early Show" anchor Maggie Rodriguez. "It could have been a jilted would-be lover. We may never know the actual reason if he is the killer. But when we have her DNA on his boots that have his name on it, when we have his green pen at the crime scene, when we have his DNA on her body and her clothing, that would be sufficient to convict him beyond a reasonable doubt."

Investigators have described Le's death as a result of "workplace violence," but the murder is not what we traditionally think of when we think of in such cases.

"Workplace violence is ordinarily a disgruntled employee who has been fired, comes back with a gun and starts shooting, goes after a supervisor in particular," Bloom said.

She described Le's strangulation death as "a very intimate kind of murder," in which the killer's hands would have been around her neck for the two to five minutes necessary to suffocate someone. "She would have been kicking, fighting, scratching, doing anything to try to save her life. There are reports by the way that he had scratch marks on his chest and on his arms.

"It sounds like a very intimate kind of killing, a male attacking a female. It sounds to me like a jilted would-be lover kind of a case. But you never know. In the annals of crime and justice there are a lot of strange stories. It's possible this is really just over a workplace dispute."

If a report that the suspect may have had help hiding the body in the wall of the Yale Medical School building is true, Bloom agreed that that person could be a major witness for the prosecution - and he or she would also be an accessory to murder. "That is really appalling, that is surprising and unusual kind of information," she said. "Usually this is a sole killer kind of situation. Hard to fathom how somebody could help him hide the body in any way if in fact that's true."

More from the Crimesider blog on the investigation into Annie Le's murder:

Was Workplace Violence Behind Killing of Yale Student?
Yale Suspect's Wedding Web Site Goes Dark
Photos: Who is Raymond Clark III?
Photos: Raymond Clark and Fiancée in Love
Photos: Yale Holds Vigil for Slain Student
Photos: Student Found Dead on Wedding Day