'Extremely dangerous' convicted murderer escapes from prison: DA

A man recently convicted of stabbing his former girlfriend to death in broad daylight has escaped from a Pennsylvania prison, authorities said.

A manhunt is underway for Danelo Cavalcante, 34, who escaped from the Chester County Prison in Pocopson Township at approximately 8:50 a.m. local time Thursday, officials said.

He was last seen on Wawaset Road in Pocopson Township around 9:40 a.m. Thursday, according to the Chester County District Attorney's Office, which warned that Cavalcante should be considered "extremely dangerous."

"His depravity knows no bounds and this is someone who has nothing to lose," Chester County District Attorney Deb Ryan told reporters at a press briefing Thursday.

Cavalcante was convicted of first-degree murder on Aug. 16 for fatally stabbing his former girlfriend 38 times in front of her two young children in 2021, officials said. At the time there was an active warrant for his arrest for an alleged murder that occurred in his native country of Brazil in 2017, according to Ryan.

He was sentenced to life in prison without parole last week for the fatal stabbing and was set to be transferred to a state correctional institution in four weeks, Ryan said.

"I don't know what he's capable of doing," Ryan said. "If he's already engaged in a murder in broad daylight in front of her two children, there's no stopping him from doing anything more egregious."

How Cavalcante escaped is under investigation, Howard Holland, the acting warden of the Chester County Prison, told reporters.

"Once we noticed we had an issue with an inmate not being there, we mainly followed our protocols -- locked down the prison, did what we call a special count to confirm there was only one person missing," Holland said.

They also locked down schools and sent out alerts to residents in the immediate area of the prison, he said.

Canine units, drones and helicopters have been deployed in the manhunt, which involves law enforcement agencies including Chester County detectives, Pennsylvania State Police and U.S. Marshals.

Ryan said Cavalcante has family in the Phoenixville area in Chester County. She said he was assisted by family and friends in escaping following the 2021 stabbing before being apprehended in Virginia, and that there are concerns about him getting help now.

"If there are any family or friends who are actively engaging in assisting him at this time, they will also be prosecuted and we're expecting them to cooperate with law enforcement," she said.

Cavalcante was described as being 5 foot, 120 pounds with black curly hair and brown eyes. He was seen wearing a white T-shirt, gray shorts and white sneakers. He is fluent in Portuguese and Spanish and speaks some English.

Anyone with information on his whereabouts is urged to call 911.

ABC News' Jason Volack contributed to this report.