A man entrusted to babysit a Brevard County four-month-old child is now facing murder charges for shaking the baby, causing his death.

Now we are hearing the gut wrenching 911 call made by Joseph Lamay as a dispatcher guided him through CPR on the young boy -- desperately trying to save the infant.

Detectives are confident he followed the directions trying to save the child.

But in the end, the boy is dead, and they say Lamay is responsible.

Lamay: I have a four month old infant and he is barely breathing and I don't know what happened to him. 

Dispatcher: What's your address?

Lamay: Oh my God, he's like..Lozenzo wake up!

Investigators said Lamay, 24, was watching fLorenzo Hernandez in the early morning hours of September 26 at the Lighthouse Pointe apartment homes in Palm Bay.

They said he was babysitting as his girlfriend worked.

Lamay made a desperate 911 call, telling dispatchers the child fell off the couch and wasn't breathing.

Dispatcher: From now on we're going to give the baby 30 pumps and two puffs. Keep doing it until help can take over. 

A dispatcher then guided him through CPR for more than 10 minutes before paramedics arrived, even mentioning him by name as she encouraged him.

Dispatcher: You cannot stop, we gotta keep going until help can take over, you're doing a good job. C'mon Joseph, we have to keep going until they take over.

The baby was flown to Arnold Palmer Children's Hospital in Orlando but died hours later. Investigators interviewed Lamay but didn't make an arrest at the time.

They later discovered the child died of blunt force trauma -- consistent with shaken baby. Lamay then changed his story.

"The description that he's giving isn't consistent with the evidence that we learned after the autopsy," said Detective Ursula Cowan of the Palm Bay Police Department.

Investigators said Lamay fled Brevard County and traveled to California where his brother lives. He was pulled over in a traffic stop and arrested on an unrelated drug charge warrant.

Palm Bay detectives headed to the West Coast themselves this past weekend and determined there was enough evidence to charge him with first-degree murder.

Detectives say Lamay took off because he didn't want people to think he did this on purpose. It could be a few weeks before he is extradited.