A corrections officer who was on duty in the guard tower when a convicted murderer escaped from a Pennsylvania prison last week by "crab walking" up a wall, sparking a massive ongoing manhunt, has been fired, officials said.

The Chester County District Attorney's Office confirmed on Friday that the corrections officer, an 18-year veteran at the Chester County Prison, was terminated Thursday afternoon. Their name was not released.

There have been multiple sightings of the fugitive -- 34-year-old Danelo Cavalcante -- since he escaped from the prison the morning of Aug. 31, including two on Friday, police said.

Cavalcante, who officials said is also wanted in his native Brazil on homicide charges, had been sentenced to life in prison without parole days prior in the fatal stabbing of his ex-girlfriend and was being held there pending transfer to a state correctional institution.

He absconded from the prison by scaling a wall to gain access to the roof and pushing through razor wire before jumping down to a less secure area to make his getaway, Howard Holland, the acting warden of the Chester County Prison, told reporters during a press briefing on Wednesday. 

He followed the same method of escape and route used recently by a different inmate at the Chester County Prison, Holland said. Inmate Igor Vidra Bolte broke out of the prison in Pocopson Township on May 19 by scaling a wall in an exercise yard to gain access to the roof, according to a criminal complaint obtained by ABC News. He was quickly captured.

Holland noted "one key difference" between the two escapes was the actions of a tower guard whose primary responsibility was to monitor inmates in the exercise yard.

"In Bolte's escape, the tower officer observed the subject leaving the yard area and contacted control immediately. That is why Bolte was apprehended within 5 minutes," Holland said. "In the escape of Cavalcante, the tower officer did not observe nor report the escape. The escape was discovered as part of the inmate counts that occur when the inmates come in from the exercise yard."

Cavalcante escaped from the prison by "crab walking" up a wall, pushing his way through razor wire installed after Bolte's escape, running across the prison roof and scaling more razor wire, Holland said.

Holland said Wednesday that steps are being taken now to completely enclose the eight exercise yards at the prison, which are now open-air. He said additional security cameras will also be installed and additional officers will be on the ground to help the tower officers monitor the inmates in the exercise yards.

Nearly 400 people from multiple agencies were working on the search on Friday, the most since the manhunt started, Pennsylvania State Police Lt. Col. George Bivens told reporters.

"We're giving this a very hard push today," Bivens said. "I'm optimistic." 

Officers shifted the perimeter west Thursday night toward Longwood Gardens after Cavalcante was sighted around noon on Thursday near the sprawling horticulture attraction, located about 5 miles southwest of the prison he escaped from, Bivens said.

There were two more confirmed sightings of Cavalcante on Friday in the search perimeter, state police said.

"We'll keep up this search at whatever tempo is appropriate for as long as we need to," Bivens said. "He's a dangerous individual."

A Chester County jury convicted Cavalcante on Aug. 16 of first-degree murder in the fatal 2021 stabbing in Schuylkill Township of his former girlfriend, 38-year-old Deborah Brandao. Prosecutors said Brandeo was stabbed 38 times in front of her two young children, ages 4 and 7.

Prosecutors said Brandao was killed after she learned Cavalcante was wanted for murder in Brazil and threatened to expose him to police, Chester County District Attorney Deb Ryan said in a statement following Cavalcante's conviction.

Following Brandao's murder, Cavalcante fled to Virginia, where he was arrested and brought back to Pennsylvania to face justice.

Bivens said Friday that Cavalcante is "desperate" but is "no stranger to hardship."

"He did something very similar to this in the jungle down there [in Brazil]," Bivens said. "It's not surprising to me that he's able to last out there for a little while."