Caitlyn Jenner -- Cops Surprised D.A. Gives Car Crash Special Attention

Caitlyn Jenner is under criminal investigation for her fatal car crash in February, and we've learned prosecutors are putting Jenner under a special microscope ... a microscope normally reserved for murderers, kidnappers and extortionists.

Law enforcement sources tell TMZ ... the L.A. County Sheriff's Dept. is a couple of weeks away from completing its investigation. The Sheriff would then normally send the case to the D.A.'s closest satellite, which in this case is Van Nuys.

But law enforcement tells us the D.A. has quietly told the Sheriff that the case will be sent to the big guns at the main office in Downtown L.A. ... in the Major Crimes Unit.

The Major Crimes Unit deals almost exclusively with extremely serious felonies. Think of the way the Navy SEALs are to the Navy. But Major Crimes will be reviewing Jenner's case, and one law enforcement source connected with the case calls it "surprising."

Law enforcement sources familiar with the case feel Jenner should not be charged with a crime at all ... Jenner wasn't texting or on the phone ... it was momentary inattentiveness that ended badly. But the sources say even if Jenner gets charged, it would certainly be a misdemeanor, not a felony.

Although the D.A. wants Major Crimes to make the final decision, it will never be filed as a felony. In the greater scheme, it's a petty case.

Fact is ... a lot of cases involving celebs end up in major crimes because they're high profile.