I fear the truth of it is that the grey areas are many. I think it just a tad naive to insist that Mark's movements were always known because that simply couldn't be the case. We only have his word for it when he was at the property and I'm afraid that means very little. His digs in London were a mere 50 miles away, about an hour in a vehicle, so plenty of time to return to the family home, do what he had to do and return to London with no-one being any the wiser.
The prosecution ruled this possibility out themselves when they established the chronology at trial. Mark could not have driven anywhere without being picked up by ANPR cameras. The police retrieved all the local taxi journals and were able to identify any occassions on which Mark travelled by train and taxi. Mark's defence team have painstakingly retraced his steps between September and December 2009, and there is strong alibi evidence. Mark simply wasn't in the vicinity of Drayton Parslow anywhere near long enough to carry out the crime.
So the prosecution set out Mark's movements at trial, and presented a detailed chronology to the jury in their document bundle as to where he was on any given day. We have been able to supplement their own sources with cash machine usage, university attendance records, records of appointments and events that Mark attended, and so on. The final picture is very finely detailed and completely evidence based. We do not need to rely on Mark's word at all.
Maybe he had an accomplice who is yet to be unmasked, a distinct possibility imo?
If you're willing to accept that Mark couldn't have acted alone, you have to be willing to accept the possibility that he didn't do it at all. The idea only makes sense in the abstract, i.e. we think more than a single person must have been involved. But that doesn't mean that one of those two or more people was Mark, because that would require actual evidence (how inconvenient!) linking other parties to what the prosecution allege Mark did, and there is none.
There is no record of any payment having been made to any contractor which leaves only one possibility.
All the employees and contractors interviewed told the police that Sami always paid them in cash.
I don't think Angelo is confusing intention with reality. The grave in which Sami was buried had nothing to do with any professional underpinning. Sami's body was entombed in a makeshift grave using three discernible levels of mortar mixes. Clearly the mortar was poured into the grave on more than one occasion thus why it was inconsistent and amateurish. It is not beyond the realms of possibility that Mark Alexander had help to carry the mortar mix to the grave and fill it in. It doesn't take much skill set to dig a hole for a body and pour a concrete mix into it before applying water.
The only layer that was identified as 'inconsistent and amateurish' was the final layer of concrete that Mark laid. This was described as "less well compacted and more voided at the upper and edge surfaces, which suggests a non-specialist installation, and the absence of shuttering".
The three layers of mortar were not described in this way. These mortar layers were "consistently well-mixed", with clear evidence of techniques like ‘levelling’, ‘shuttering’, and ‘compacting’ having been used. "The mix quality, consistency (both thoroughness of mixing and degree of compaction) of the various mortar layers suggests preparation by an experienced person".
Similarly, the excavation itself was quite unusual:
"A gully of loose bricks and rubbish could also be seen to have been cut through in order to dig the large hole... The root system of a tree had been cut down... [and] cut away in order to excavate the hole... [The site was] apparently not designed as a grave... Not all the excavated length was utilised. It may be an indication that other means were first used to dispose of the body, but after the grave had been dug. The maximum depth was 1.2m... [It was] well-constructed, by someone who appears to have known what they were doing"Recent analysis by experts has revealed the degree of effort required. We cannot disclose the findings of this latest report in great detail because they will be subject to legal proceedings, but the main thing to take away from it is that this would have been back-breaking and time-consuming work. They've given an estimate of just how long it would have taken, and the excavation alone exceeds the amount of time that Mark was actually in Drayton Parslow.
http://www.freemarkalexander.org/faq/#construction IMO one thing is certain though and that is that Mark Alexander had no involvement in any building work while his father was away, Sami would never have allowed it for one thing.
There was evidence at trial of a number of occassions when Sami had asked Mark to deal with contractors visiting the house on his behalf prior to this, to supervise their work, or to collect materials he had ordered from depots.
The only reason Mark Alexander ordered Ready Mix concrete was to cover up what he had a already done. The concrete lorry driver even observed that his customer was literally out of his depth and had very little real knowledge of what he was doing.
Again this just doesn't seem consistent with the way the first three layers were installed. If Mark was involved from the beginning, why would he change materials? Why not just stop at the third layer? Why would he change his modus operandi, making the bizarre switch from clandestine to public? If he had been mixing and laying mortar to a professional level previously then he would have had plenty of practice with a wheelbarrow and would have appeared proficient to the lorry driver.
Most critically, why is their no forensic evidence? None of Mark's DNA or fingerprints appeared on the plastic bags found within the mortar. Nor had he washed his rough work clothes. Had he been involved in the burial then residue from the body would have been left on his clothes. Had he been mixing and laying mortar then particles of this would also have appeared on his clothes.