MANITOWOC, Wis. -- A cousin of the teenager on trial in Manitowoc County for sexually assaulting and killing Teresa Halbach testified on Wednesday that she made up conversations she had with Brendan Dassey about the case.

Kayla Avery, 15, initially told investigators and others that Dassey told her that he saw body parts in a bonfire at Steven Avery's home the night that Halbach disappeared. Kayla Avery also denied on the witness stand that Dassey told her that he saw Halbach tied to a chair in Steven Avery's trailer.

She testified that Dassey changed in the months after Halloween 2005 when Halbach was murdered, and wasn't as outgoing.

"He didn't tell me anything," she said on the stand. "I kind of made up the statement. And I'm sorry."

The 17-year-old Dassey is charged with raping and killing Halbach and disposing of her body. His uncle, Steven Avery, was convicted last month of killing Halbach.

Kayla Avery told defense attorney Mark Fremgen that she made up the story about her conversation with Dassey after hearing news reports about the burn pit, where Halbach's remains were found.

Halbach, of St. John in Calumet County, disappeared on Halloween 2005 after going to the Avery family's salvage lot to take photos for Auto Trader Magazine of a van that was for sale.

Authorities said that Dassey confessed to his involvement four months after Steven Avery was initially charged in the killing. He allegedly admitted to joining Avery in raping Halbach, killing her and burning her body near the property.

Dassey later recanted his confession in a letter to the judge and refused to testify against his uncle.

Avery's rape, kidnapping and false-imprisonment charges have been dismissed for lack of evidence.

On Tuesday, arson investigator Kevin Heimerl of the state Division of Criminal told jurors how he found a bullet fragment in the garage of Steven Avery in March 2006. He said that he didn't see the bullet fragment when he searched in November 2005.

The investigator said Dassey's statements a year ago detailing the death led authorities to certain pieces of evidence in the garage. Although Dassey later recanted the statements, Heimerl said that when he went back to the garage, he saw a gray item that looked like a bullet.

Later tests found Halbach's DNA on it, authorities said.