A man was killed in a roundhouse with no doors or windows. 
Four maids were present at the time of the murder, but are saying nothing. When asked what they were doing they replied as thus:

Maid 1: 'I was making the tea.'  

Maid 2: 'I was dusting the mantelpiece.'  

Maid 3: 'I was setting a mouse trap in the corner.'  

Maid 4: 'I was watching the telly.' 

One of the maids has lied. The liar is the murderer. 

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> Who is the murderer and what is the lie? 
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