Wellington Police say are focusing their investigation on the Newtown address where a 37 year old man died yesterday.
ESR and Police staff will conduct a forensic scene examination at the Mansfield Street residence as part of their inquiries. The scene examination may take some time to complete.
Detective Inspector Paul Basham says he is interested in speaking with further possible witnesses who may hold information about what happened.
"We would like to speak with a male who lives at the residence who has yet to speak with Police.
"In addition we would also like to speak with a female who called Police prior to the incident yesterday morning.
"Both of these people may hold important information and be able to help with our inquiries. We'd like to hear from them as soon as possible," says Mr Basham.
The arrested man was not a relative of the deceased but both lived in the residence. Both have interim name suppression until Friday.
A post mortem will take place today with results due in the following days.
Anyone with further information is urged to call Police on 0800 TIPOFF (0800 841633).