PHILADELPHIA (CBS/AP) — Pennsylvania State Police say they have seized supplies of food belonging to the survivalist charged with ambushing a rural police barracks. They say he will likely have to start breaking into cabins or searching through trash bins to sustain himself.

Lt. Col. George Bivens says police found a campsite recently used by 31-year-old Eric Frein. He says police found tuna fish, instant noodles and other food as well as 90 rounds from a rifle of the same type used in the deadly ambush.

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Bivens says authorities are pushing Frein hard. He believes the suspect will have to resort to looking for food in vacant cabins and trash bins at restaurants and grocery stores.

WEB EXTRA: Officials Update On Manhunt For Frein

Bivens gave an update on the manhunt Friday, three weeks after the shooting that killed Cpl. Bryon Dickson and seriously wounded Trooper Alex Douglass.

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“Again, we remain confident Frein is in the general search area near the border,” said Bivens. “However, we need to follow-up on all information available to us – these may include areas where investigators have been told Frein has frequented in the past.”

Authorities say that area residents with access to cabins or campsites who notice items missing or in disarray should exit the premises immediately and call police. Businesses are also asked to be on high alert.

(TM and © Copyright 2014 CBS Radio Inc. and its relevant subsidiaries. CBS RADIO and EYE Logo TM and Copyright 2014 CBS Broadcasting Inc. Used under license. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed. The Associated Press contributed to this report.)

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