I must concur with those posters who have seen a 'ritualistic' element in the combination of shoes placed beside her, concrete slab placed on her abdomen and her body placed in the hearse.
Seems to me a kind of "burial" ritual. Almost reverent. I'd be interested in any reports concerning local mental patients with a history of violence, religious mania or harassing women, possibly recently released from hospital or jail at the time.
Something (mainly that the location took some effort to get to, rather than a vacant house or lot with more convenient, faster access) tells me the hearse was known to this person, it meant something to them (personally or symbolically) and that they were probably local.
Bizarre ritual says to me: the guy may have had mental problems. It's possible he was locally treated for those.