Olathe ? Prosecutors are defending the methods police used in their pre-arrest surveillance of accused serial killer John E. Robinson Sr.

Attorneys for Robinson are asking a judge to disallow evidence found during a search of Robinson’s 16-acre property in Linn County, including the bodies of two of the women he allegedly killed.

Robinson, 58, of Olathe is scheduled to go to trial in September in Johnson County District Court on charges that he killed three women. He could be sentenced to death if convicted.

A Lenexa police detective illegally trespassed on Robinson’s property March 30, 2000, the defense contends. Because information obtained from that visit was used to support a later search warrant, all evidence obtained in the search should be thrown out, the defense argues.

But Lenexa police Detective Dawn Layman testified at a hearing earlier this month that authorities did not yet know who owned the parcel of property when they followed Robinson there March 29.

Layman returned the next day, taking photographs, including pictures of license plates on two vehicles in an effort to identify the land’s owner, she said.

Among the photographs she took were of barrels next to a shed. In the June 2000 search, the bodies of two women were found in the barrels.

In their response to the defense challenge, prosecutors Paul Morrison and Sara Welch argued that nothing the officer did that day violated the law. The officer specifically noted that no “no trespassing” sign was posted on the property, and nothing blocked the gravel driveway that led to the property.

“Taking photographs, walking around an empty trailer in an open field and following a suspect in a car are not exercises of law enforcement ‘power,”‘ according to the memorandum.

A hearing on the defense motion is scheduled for Thursday.