Police probing the death of Steven Allford - the Brit found dead in Malaga with ham on his buttocks - believe he was 'killed by another homeless person in row over food'.
It's now nine says since his body was discovered outside Malaga Airport - bound to a bench with his trousers pulled down and body showing signs of abuse including his genitals inside a can of tuna.
See also: British man found dead at Spanish airport with trousers down
And police have been stumped over how he came to be there - with theories ranging from it being a 'stag do prank gone wrong' to some kind of 'hate crime'.
But investigators are said to now believe the homeless Brit may have been targeted by a fellow vagrant following a brewing row over food.
A specialist prosecutor had taken on the bizarre case to investigate whether it could have been a hate crime - centred on the victimisation of homeless people.
And a Finnish vagrant was arrested on Friday on suspicion of Mr Allford's manslaughter.
Allford's acquaintances are reported to have told police he made several enemies by refusing to share meals with other vagrants - but expected their food when it came their way.
The MailOnline reports that investigators are working on the theory that the ham and tuna may have been a "crude message left by those he had upset".
The unnamed Finnish national, said to be aged around 50, was held on Wednesday at an undisclosed location.
He has already been remanded in jail pending an ongoing judicial probe following a private court hearing before an investigating judge.
A source close to the case described the suspect as a "well-built giant."
It is not know what his relationship, if any, was to the dead man.
The source said: "He is being investigated at this stage on suspicion of a crime of manslaughter although that could change as the judicial probe progresses."
Further arrests have not been ruled out.
Mr Allford's body was discovered by a security guard just before 9am on Friday October 21. He was found in a landscaped garden between Malaga Airport's train station and terminal building.
He had been bound face-down, with cable ties attaching an arm to one end of the bench and a leg to the other.
His trousers and pants had been pulled down, ham placed on his buttocks and his privates wedged into an open fish can.
News of the detention came shortly after it emerged a prosecutor specialising in hate crimes had agreed to take on the bizarre case and police were hunting three men seen with Mr Allford, who was sleeping rough at Malaga Airport, on the night he died.
The specialist prosecutor agreed to investigate the strange death after a complaint from a homeless support organisation.
Observatorio Hatento, an amalgamation of several charities across Spain which work with homeless people, says Mr Allford's death could be a hate crime based on hobophobia - a fear of vagrants.
A post-mortem revealed Stephen had choked to death on his own vomit.
A sexual attack has not been ruled out because of the circumstances in which he was found - tied face-down to the bench with his trousers pulled down and a slice of ham placed on each of his buttocks.
The fact the suspect is being investigated at this stage on suspicion of homicide means the authorities think Mr Allford may have been bound to the bench before he died.
His body was discovered just before 9am last Friday in a landscaped area of Malaga Airport by a train stop well-used by tourists and opposite the arrivals lounge.
It is not known where in the UK Mr Allford was originally from, although he is believed to have spent some time living in Spain. Investigators have discovered he has a conviction for fraud from a court in Catalunya.
The prison the unnamed Finnish suspect has been sent to - Alhaurin de la Torre near Malaga - is understood to be the jail Mr Allford also served part of his sentence in after being convicted.