Iowa cops have pulled out the legal guns to locate the vehicle that took 'Bachelor' Chris Soules from the scene of the fatal crash.

TMZ has obtained documents showing police have obtained a search warrant for the red Chevy. As we reported, after calling 911 and then checking the pulse of the tractor driver who later died, the Chevy came along, Chris jumped in and left before cops arrived.

Cops want the Chevy as evidence, although it's unclear why. Since the accident occurred Monday, any alcohol present in the vehicle would be irrelevant, since it would not prove what was inside at the time of the accident.

Cops are clearly interested in the results of the blood tests that were taken at the hospital hours after the accident. The search warrant allows police to obtain the results from the hospital.

As we reported, police want to know if Chris was under the influence of drugs or alcohol at the time of the crash. Problem is ... when cops found Chris at his house he refused to come out until they got a search warrant, so the blood test results would not reliably show Chris' blood alcohol level at the time of the crash.