Police said the search, which began at about 5 p.m. and ended shortly after 7:30 p.m., turned up no clues.
Police were told today of a van that matched the suspect vehicle in the abduction of Heeringa was seen in the state park on Saturday morning, and gun shots were heard in the park at about the same time. Police closed the park for a short time at around 2 p.m. Thursday, then reopened it.
"Today we received a tip of gun shots on Saturday morning in the area of P.J. Hoffmaster State Park in the City of Norton Shores," Norton Shores Police Chief Dan Shaw said shortly before 5 p.m. Thursday. "Though we believe the tip is credible, please understand that Saturday was opening day of turkey hunting season and hunting is allowed in the southern portion of our city. We have no information connecting the gun shots to the Jessica Heeringa case, but we have organized an aerial and ground search of the area."
The park was closed to the public during the search.
A state police helicopter conducted an aerial search of the park and the adjacent North Ottawa Dunes shortly after 5 p.m. A ground search focused on the middle of the 1,200-acre state park.
The helicopter also searched an area north of Muskegon on Thursday, based on another tip.
A TV reporter handed Shaw a pair of glasses that he said were found by a man at the state park, and that they looked like Heeringa's. The missing woman's fiance verified that they were not Heeringa's glasses, as he has frequently fixed them for her.
Police believe Heeringa, 25, was abducted from the Exxon Mobil gas station on Sternberg Road when she was closing the store late on April 26. The Norton Shores woman has not been seen or heard from since then.
The Exxon Mobil Corp. has donated $15,000 toward the reward offered in the case.