A post mortem examination will be carried out today to determine the cause of death.
About 40 police staff are involved in the homicide investigation, which is centred on a detailed forensic examination of the house where Mr Round's body was found.
Police yesterday also searched the banks of the Whanganui River in relation to the investigation.
They would like to hear from anyone who saw the victim's distinctive blue Jaguar on Wednesday evening or Thursday morning. Police were also trying to find some items of clothing.
Mr Round spent much of his career as a news agency journalist for both the New Zealand Press Association (NZPA) and Reuters.
He was one of the last New Zealand journalists to leave Saigon as the Vietnam War came to an end and later became Asia correspondent for NZPA in the 1970s.
Later roles at NZPA included political editor at the parliamentary press gallery, London bureau chief, and editor - a role he held for five years from 1984 to 1989.
Former Reuters colleague Nick Turner, who also worked as a reporter in Asia in the 1960s, said Round's death was "all very sad''.
As a reporter, he had built up "a huge knowledge'' of New Zealand politics.
"He had quite a formidable memory ... He just had that knack of being able to remember things in detail and very accurately,'' Mr Turner said.
"He became quite an authoritative person on a lot of issues because he just did have this recall of events and people.''
When Round covered the last days of the Vietnam War, he used his political contacts to try to make a difference.
"I'm not sure how successful that was, but I do know that because he had very good contacts with a lot of New Zealand politicians, he tried to pull some strings to get additional measures taken to evacuate people with New Zealand connections.''
Former NZPA colleague Max Lambert said Derek Round liked the social side of journalism.
"He was an excellent reporter and an excellent writer ... He stood up to Muldoon a number of times.''
Mr Round's children took after him professionally, with son Mark Round working as pictures editor for the Dominion Post and daughter Sally Laven working for Radio New Zealand.
Round lived in Masterton after retirement before moving to Wanganui.
A neighbour, who did not want to be identified, said Mr Round had moved into the house, part of a block of semi-detached homes, only about a month ago.
She was not aware of the police presence in her street until she came home from work and was asked to give a statement.
"Poor man, it makes me feel scared and unsafe,'' she said.
"It's usually quiet, this area, it's shocking.''
A resident of nearby Ingestre St, who also did not want to be identified, said she heard a loud bang coming from the flats as she was trying to get to sleep on Wednesday night.
"It sounded quite near, like wood banging on something, just an upsetting noise because I got up to see if I could see anything but I couldn't,'' she said.
