Jessica Heeringa Update: Authorities believe they can find missing Mich. mom, police chief says

(CBS/AP) NORTON SHORES, Mich. - A West Michigan police official says he believes authorities will find Jessica Heeringa, a 25-year-old gas station clerk who went missing on April 26 while working the night shift.

PICTURES: Mich. mom vanishes from gas station

Norton Shores Police Chief Daniel Shaw said Tuesday it gets harder as time passes to solve the case involving the disappearance Friday of Heeringa. But he says investigators continue to pursue leads and examine limited evidence.

Among the evidence is surveillance video from a nearby tavern in Norton Shores, Mich., where police say the mother was abducted. The short clip shows a silver or gray Chrysler minivan driving away from the scene and traveling north.

Shaw says that bolsters a witness' description of a similar van parked near the station. He says the video doesn't show people inside or a license plate number but witnesses have described the driver as a white man, age 30 to 40, about 6 feet tall, with light brown wavy hair.

The gas station where Heeringa was working did not have a security camera and there were no signs of a struggle or robbery, though police are treating the case as an abduction.

Police described Herringa as 5-foot-1 and about 110 pounds.

Anyone who may have witnessed suspicious activity near the Exxon Mobil gas station in Norton Shores, Mich. is asked to contact Silent Observer at 231-72-CRIME (231-722-7463) or call 911.

Complete coverage of the Jessica Heeringa disappearance on Crimesider