There have been at least 8 sightings of Pennsylvania convicted killer Danelo Cavalcante since his escape, police say

The convicted murderer who broke out of an eastern Pennsylvania prison last week has been spotted at least eight times, authorities confirmed Thursday, but he remains elusive as searchers try to navigate extreme heat, high humidity and the landscape.

Danelo Cavalcante was spotted by a resident in a creek bed on Tuesday night but fled into the woods before police could capture him. That spotting was in an area of Chandler Road in Pennsbury Township, about 2.5 miles southeast of the Chester County Prison. Search teams scoured the area for hours but were unable to locate him, Pennsylvania State Police Lt. Col. George Bivens said this week.

Cavalcante may also have been seen just before noon Thursday in the area of Longwood Gardens, a popular botanical garden nearly three miles from the prison, where he was spotted on security camera earlier this week, Bivens said during a Thursday news conference. An individual reported they saw someone matching the escapee's description running through the area, Bivens said, adding searchers are now at the location.

"We're using people on foot, we have horses out there as well that are assisting with the search, tactical teams, and of course the aviation assets," he said.

Cavalcante has been on the run since August 31, when he escaped from the Chester County Prison in a rural area some 30 miles west of Philadelphia. Now in its eighth day Thursday, the search for him has unnerved county residents who've been told he's extremely dangerous.

Authorities have also upped the reward for information leading to his arrest to $20,000. They believe he remains within the perimeter they are searching - an area which is about eight to 10 square miles, according to Bivens.

"We have maintained as secure a perimeter as we possibly could and as recently as today we have another reported sighting," he said, referring to Thursday's potential sighting.