Jurors saw security footage Tuesday of the 19-year-old on trial for allegedly killing his friend's grandmother depositing a check she wrote him before he strangled and stabbed her.

Prosecutors say Brok Junkermeier killed 79-year-old Lila Warwick after forcing her to write him a check for $1,500 -- writing in the memo line "college expenses."

A teller testified to "chit-chatting" with Junkermeier as he made the deposit. "He said the check was from his grandmother," said Traci O'Connell, a teller at Bremer Bank. "I said that was nice that she was helping him out."

This afternoon, jurors are expected to see a four-hour, videotaped interview of Junkermeier confessing to investigators.

Brad Redmond, a detective sergeant with the Kandiyohi County Sheriff's Office, said that two days after Lila Warwick's death, investigators approached Junkermeier at his work and drove him to the sheriff’s office. Prosecutors said that Junkermeier confessed during the following four-hour interview, saying, "I killed Lila Warwick."

Afterward, Junkermeier allegedly brought the investigators to a spot in the country where he had discarded a knife and sweatshirt.