Adapted and reposted.
The fairs could be the common denominator.
1 - November 2018, NM commits sexual offence in Newport Pagnell in or around time fair is on at Campbell Park, MK.
2 - LC goes missing near to Valentine's fair at National Bowl, MK when it is on February 2019.
3 - NM passes away in April 2019, even though he travels across the UK it is at the same location fair is held in November and a few miles from where LC is discovered. Not sure where the fairs are at this point in time, they're not in MK but could be nearby. Currently, it is not known by what means he used to commit suicide.
4 - Hayden passes away in November 2019, this is ruled a suicide and I believe it was by hanging. This occured around time fair was back on again in November, this was the same fair company as the previous November. I believe this occured in nearby Bletchley and he lived alone.
If NM is friendly with some people at the fair (other possible sexual offenders), I could quite imagine him boasting about how he has access to a 500k house and letting them them stay there while the fair is on, possibly even cutting/ giving them keys. We're not sure if NM knew what happened at the house, for all we know he could have discovered the body at a later date in April. As yet, no one has actually witnessed him having any contact with LC.
If they stitched him up i.e. whether they did it with or without him, they would have motive to harm him (he would also be fearing his arrest regardless). He is the only one connected to the house, and it may only be him that connects them to the house. They would also most likely know the owners are returning in a few months time too.
If or how the the brother is connected I don't know. Did he know NM? Did he know people at the fair? Even though it was a different fair to one in February (they may share workers), did he ask questions around the fair when it returned in November 2019, he was clearly affected by her disappearance and determined to locate her. Was any of this an influencing factor in his suicide in November??
It's also worth noting that we have three events, two suicides and a murder. These occured within eight months of eachother just four miles apart. The two suicides are by people who seemingly didn't know one another who are then connected three years later by another persons murder. All of these incidents are seemingly connected to two different fairs by locations or times.