PORTLAND – After hearing two days of testimony, a judge has denied bail to a 20-year-old man charged with murder in connection with a fatal stabbing last fall at a Congress Street apartment.

But while he found probable cause for the charge against Brandon Mills, Superior Court Justice Thomas Warren cited potential weaknesses in the prosecution’s case. He said testimony by a key witness, the victim’s brother, was “inconsistent” and “hostile in some respects.”

Mills is charged with killing Jarmaine Ramirez, 16, during a fight that began when Mills and his brother Antwane, 18, entered the apartment building on Oct. 21 after children in the Ramirez family’s second-floor apartment threw water out a window onto the younger Mills.

A murder charge against Antwane Mills was dropped as part of a plea agreement in which he pleaded guilty to burglary and assault.

Warren’s ruling on probable cause came Friday after a bail hearing in which most of the witnesses against Mills were questioned by the prosecution and defense.