Susan Blyth Neill-Fraser, 56, has pleaded not guilty to murdering Bob Chappell, who went missing from the couple's yacht Four Winds on January 26, 2009.

Detective Senior Constable Shane Sinnitt, of Hobart CIB, said Ms Neill- Fraser told him on February 5, 2009, that she went to the yacht, which was moored on the Derwent River in Sandy Bay, on the afternoon of January 26 and that she argued with Mr Chappell because she was in his way.

Senior Constable Sinnitt said Ms Neill-Fraser told him she then left the yacht, where she said Mr Chappell would spend the night, and went to Bunnings at Derwent Park before returning to her West Hobart home.

The court heard Ms Neill-Fraser gave Senior Constable Sinnitt a description of what she was wearing.

He said he reviewed security footage from the store taken that afternoon but did not see Ms Neill-Fraser.

He said he had a further conversation with Ms Neill-Fraser on February 16 when she told him that the yacht, which she and Mr Chappell had bought in Queensland, had been broken into.

"She stated that she believed the disappearance (of Mr Chappell) was related to break-ins on the yacht both in Queensland and on the mooring at Sandy Bay," he said.

He said Ms Neill-Fraser telephoned him on April 28 to ask about the search of an area of the Derwent undertaken by Victorian Water Police.

"She asked if the fire extinguisher off the vessel had been located. She also asked if we found anything else," he said.

He said Ms Neill-Fraser was arrested on August 20, 2009.

Senior Constable Sinnitt said he also investigated a DNA profile found on the deck of Four Winds that matched that of a 16-year-old girl.

He said that although police had been unable to ascertain her whereabouts on the night of January 26, 2009, there was no evidence in addition to the DNA that linked her to the boat.

He said a large quantity of fingerprints were lifted from Four Winds during the investigation but none matched those of the girl.

The trial continues.