BATON ROUGE - The boyfriend of a missing pregnant woman was booked for murder after he confessed to killing her and throwing her 2-year-old son over a bridge and leaving him to die.

Brynnen Murphy, 20, was booked on two counts of first-degree murder. A judge ordered Tuesday that he remain jailed without bond.  Police said they'll likely pursue feticide charges against him, too. 

Police said Murphy told investigators where he dumped the bodies of 24-year-old Kaylen Johnson and her son Kaden, prompting searches at two separate locations in East Baton Rouge early Monday afternoon.

Kaylen was found around noon in a wooded area along Burbank Drive near Gardere Lane. Her son's body was found a short while later along Central Thruway, south of Frenchtown Road. Police believe both bodies had been dumped about a week ago.

Kaylen Johnson had been shot multiple times, the coroner said, after an autopsy Tuesday. 

Sources told WBRZ Murphy confessed to shooting and killing Kaylen in the parking lot of his apartment complex on North Harrells Ferry Road. Murphy then allegedly ditched the gun in the same wooded area where Kaylen was found. Kaylen's son Kaden was reportedly in the car when his mother was shot and when Murphy dumped her body.

After disposing of his girlfriend's body and the murder weapon, Murphy drove to the Central Thruway where he threw Kaden—who was still alive—over the bridge. Sources told WBRZ Murphy heard Kaden crying as he drove away.

In a preliminary autopsy, the coroner said the child likely died as a result of hypothermia, though further analysis is being done.  

After throwing the child over the bridge, Murphy abandoned Kaylen's vehicle on a dead-end street near his apartment off North Harrells Ferry. 

Click here to see video of Murphy being taken into custody

Law enforcement began searching for the mother and child over the weekend after family reported them missing. They said Kaylen, who was six months pregnant, had not been heard from since March 5. That's when police suspect she was shot and killed. 

"She told her friend that she had just made it home. She wanted to take a bath and get something to eat, and that was the last time anybody heard from her," said April Johnson, Kaylen's mother.

Kaylen lived in an apartment on Old Hammond Highway. After their disappearance, Kaylen's car was found near an apartment complex on Sherwood Meadow Drive, one of the first signs that something was wrong.

"We looked inside, and the seat was all the way back. She's short. She can't drive like that, and she can't see. So she sits up under the steering wheel," said Tiara Johnson, Kaylen's sister.

Family members said Murphy, who was a property maintenance worker at Kaylen's apartment complex, was babysitting Kaden the day both disappeared.