A Little Falls man serving two life sentences for killing two unarmed teenagers suspected of burglarizing his home has been denied his final appeal.

Byron Smith, 72, was convicted in 2014 of four counts of murder for killing cousins Nicholas Brady, 17, and Haile Kifer, 18, on Thanksgiving 2012.

Prosecutors argued that Smith, whose home had previously been burglarized, sat armed and waiting in his basement and coldly executed Kifer and Brady as they descended his stairs about 10 minutes apart, continuing to fire after they no longer posed a threat.

Smith claimed he was defending himself and was fearful after having guns stolen in prior burglaries.

The case drew national attention amid debate over how far a homeowner can go to defend himself and his property.

The U.S. Supreme Court rejected his appeal on Monday.

At the core of it, Smith argued that a Morrison County District Court judge violated his right to a public trial by temporarily closing the courtroom during his April 2014 jury trial.

Associate Justice Sonia Sotomayor wrote in a dissenting opinion that the Minnesota Supreme Court was wrong when it ruled that so-called administrative proceedings can be closed to the public.

In a brief submitted to the Eighth Circuit, opposing Smith's appeal, Minnesota officials said the nonpublic proceeding did not violate the Sixth Amendment because the proceeding was not part of the trial.

When reviewing Smith's petition, the U.S. District Court for Minnesota observed that the closure during Smith's trial is part of a "broader and disturbing trend" in Minnesota. Minnesota Supreme Court justices have expressed alarm about "creeping courtroom closure."

Sotomayor said she shared those "well founded concerns."

Staff writer Stephen Montemayor and the Associated Press contributed to this report.

Alex Chhith • 612-673-5749