From maps it would seem possible that the individual arrested and LS could have easily crossed paths in the local area. The shops, pubs and takeaways around Cottingham Road/Clough Road/Beverley Road crossroads would have been local to both of them. Also, Beverley Road is the route north towards the arrested gentleman's place of work in Malton as well as the University of Hull. Could he have seen LS waiting for a bus or walking to and from the University on a number of occasions? Had he offered her lifts in the past?
Did his homelife force him out of the house at odd hours? By that I mean having had two lovely children myself I remember sometimes finding the endless care and attention at times suffocating when they were very young. It is probably a man thing (my wife is astounding) but I did go for drives to clear my head at 'odd times of the day and night' when regularly woken by crying babies. Did he chance across LS whilst doing something similar or going to/returning from work? (Meat processing especially on a large scale is a 24 hour a day undertaking).
Also, and this in no way excuses anything, having recently become a father again was he getting no 'attention' from his wife?
The Oak Road Playing Fields and the pond and abandoned buildings are accessible by road via Beresford Avenue and are a very direct route from Raglan Street or Wellesley Avenue. There is a gate baring access on Oak Road so was this forced or open to allow a car in? There would also appear to be access through an adjacent car park.
IMO this all looks like an opportunistic event to me, a perfect storm of unfortunate circumstances (possible home and work stressors on one hand and a largely incapacitated victim possibly known albeit by sight on the other) that have ended in an increasingly likely tragic way.