So, you're probably wondering why I believe Niamh to be the killer? But, why listen to my opinion, when I could showcase to you the cold, heavy evidence?
Snooping through Niamh's personal drawer, I overcame something of interest. A diary, if you will, showcasing some disturbing images drawn by the killer herself; Niamh. I do not understand why the pictures exist, or why they weren't hidden in a better place. All I can present to you is what I have discovered.
http://i.imgur.com/vS7A4Bnl.jpg
This first picture seems to depict Niamh along with a number of objects, some covered in blood... A knife, a rag, a potato... surely the latter must give it away? Perhaps it shows what she brought with her in her suitcase? The 'hip pills' prove that this picture was only drawn by one person...
http://i.imgur.com/KmdLZdol.jpg
This image shows what seems to be a now dead Michaela with multiple stab wounds in the chest, with Niamh holding a knife. It is written how she has been stabbed for stealing Niamh's potato... the potato in question was last seen 43 minutes before Michaela's death. Did Michaela feel peckish and paid the ultimate price?
http://i.imgur.com/3zE9gH3l.jpg
This grisly picture shows what seems to be Sofia drinking an alcoholic subtance, which Niamh believes belongs to her. Being the Irish lady that she is, it is very believable that seeing Sofia with her drink was enough to make her snap. As for the noose? It was found around Sofia's neck.
http://i.imgur.com/hzFfaUwl.jpg
Jonas was found drowned in a toilet, marking the next death. Before this, niamh had been moaning that her '65+' pills had gone missing, which she takes daily to help constipation. Was it possible that she found Jonas with her pills, quickly took the pills to poo in the toilet and drowned Jonas afterwards? Is the Catholic Church a bit dodgy?
http://i.imgur.com/yNmr4iXl.jpg
After Netta was discovered with 3rd-degree burns, Niamh was nowhere to be seen, with her cover story being that she was playing Scrabble (on your own? no dear), but this picture drawn by Niamh shows otherwise, with Netta being burnt to a crisp with a blow-torch.
http://i.imgur.com/F2NbjCOl.jpg
It was assumed that Niamh and Haley were pretty close friends in this cell, but this lovely drawn picture shows us otherwise. What with Haley being killed with a blunt object, Niamh's reasoning for doing so seems to have been her new pink hair colour, which Haley had asked Livia to do for her instead of Niamh. Clearly, Niamh didn't take to this news kindly.
http://i.imgur.com/8GzrB29l.jpg
The last image found in Niamh's 'diary' depicts Niamh killing her latest victim by stabbing him in the chest multiple times after using chloroform to knock him straight out. Perhaps he insulted her dress sense, perhaps he didn't share his wine with her over dinner, or perhaps he knew too much?
The evidence above is overwhelming, understandably. Could Niamh have drawn these is moments of sadness, knowing that she couldn't tell anybody else apart from life-less paper? Perhaps. What is clear, however, is that Niamh is the killer