Pretoria, South Africa (CNN) -- The prosecution and defense have made their cases, and now Judge Thokozile Masipa must decide: Did Oscar Pistorius intentionally kill his girlfriend Reeva Steenkamp? Was it murder? She will begin reading her decision Thursday. The judge has to answer several questions to reach her verdict on the murder charge, one of four charges Pistorius faces. First -- and most important -- did Pistorius know Steenkamp was behind the door in his bathroom when he fired four shots through it on Valentine's Day last year, killing her? If the answer is yes, beyond a reasonable doubt, Pistorius knew he was shooting at his girlfriend, then the judge will find him guilty of murder.
@highlight
Judge Thokozile Masipa must answer several questions to determine her ruling
@highlight
If Pistorius knew he was shooting at Reeva Steenkamp, he committed murder
@highlight
If he did not, the verdict hinges on whether Pistorius acted reasonably
@highlight
The sentence could be anything up to 25 years, depending on the verdict
If she thinks the murder wasn't premeditated, @placeholder could get a minimum of 15 years behind bars.