When you mention his name to the grey-uniformed cop on the gate, he stares hard into your face - but not as hard as Mr Tosic does. All of 7ft tall, he sits beneath an icon of the Archangel Michael holding a bloody sword, and extends a hand as big as a dinner plate. Back in July, a Muslim was done to death a few feet from where Mr Tosic is sitting, but today is good-manners day.
"I welcome you to my office because my general cultural level and my appreciation of your honourable newspaper allows me to do so," he begins.
This was certainly not the welcome that Hassan Kovacevic received here on 30 July. But then again, I haven't yet mentioned how Mr Kovacevic was dragged from here to hospital with 16 broken ribs. Indeed, I haven't even told Mr Tosic why I am here.
But he guesses. "Unfortunately," he goes on, "there are certain rules and regulations and, according to positive [sic] law and our constitution, I am not entitled to give any information to any public media. Did you come here by chance, or for any particular reason?"
Well, I said gently, there was - was there not? - an unfortunate incident back in July at Police Station No3.
Mr Tosic watched me for all of five seconds. He knew what I meant and replied, very slowly. "Our police inquiry into this matter was completed as far as it concerned police procedures. But I am again not entitled to speak about results. We have to be professional, according to laws and procedures."
A railway worker's son, Commander Tosic was being discreet. Why not go down to state security headquarters and chat to Stojan Davidovic, commander of all Banja Luka's police sectors? I did. Mr Davidovic was busy. Then his phone was engaged. Then he was - a likely story - "out of town on business".
A policeman's lot, it seemed, was not a happy one. Nor was that of Mr Kovacevic. Everyone agrees the argumentative Muslim had been arrested by the Serb police on 30 July for allegedly shouting abuse at a Serb woman near his home. He was taken to Police Station No3. And then, after interrogation, he was driven at midnight to the local hospital.
Doctors discovered he had sustained 16 broken ribs and was bleeding internally. They ordered that he be taken home at once. But the cops took him back to Police Station No3 where, at four in the morning of 31 July - presumably after another spot of interrogation - he was found dead, covered in blood, on the floor of a cell.
The inquiry, needless to say, tells a slightly different story. Mr Kovacevic had sustained his injuries while resisting arrest.
The police were unaware of the gravity of his wounds - 16 broken ribs not being obvious to them - and while the cops may have been a trifle negligent in reporting that he was sick, no blame could be attached to them.
Even the United Nation's International Police Task Force (IPTF) found this a little hard to take. Their inquiries revealed, for example, that the woman whom Kovacevic had allegedly insulted was the mother of a local policeman. They found that the policeman in question was under Mr Tosic's command. And that this very same policeman was on duty on the night of Mr Kovacevic's interrogation at Police Station No3. Would the IPTF like an exhumation, the Serb police asked (exhumation being all the rage around here at the moment).
Then the international observers would find - said Mr Tosic - that the police who arrested the Muslim had used only rubber truncheons. This observation, on the IPTF's report, is followed by a well-merited exclamation mark.
The UN says it does not believe the dark secret of Police Station No3 marks another chapter in "ethnic cleansing". New Serb policemen, uncontaminated by the horrors of the recent past, have arrived from Banja Luka's police academy. And Kovacevic was known to be an argumentative soul. His wife refused to assist the police inquiry although, given the circumstances of her husband's death, this might have been a judicious decision.
It would be pleasant to believe this was just a shadow of the past, an isolated, regrettable incident that can be overlooked. If only that were true.
Up in Bosanska Gradiska, for example, some 20 miles from Banja Luka, the police are backing the local Serb authorities in the continuing "legal" expulsion of Muslims from their homes. In the local graveyard at Dubrava, you can find the last resting place of Asim and Senija Mujic. Asim was 96 and his wife 73 when they were ordered from their home by Serb refugees who held documents from Serb authorities entitling them to the house. The couple were forced to live in a garage in sub-zero temperatures - Asim had been bedridden for nine years - until in February, Red Cross officials rushed them to a Banja Luka hospital. Asim died first, his wife 15 days later.
Meira Galic, who was 78, was thrown out of her home in 1995 and died in an institution in May. In April this year, 83-year old former partisan Sacir Kovacevic was ordered from his home and died almost at once. That same month, 75-year-old Mohamed Hatic was ordered from his home along with his disabled son, who can only move in a wheelchair. Mohamed died in July. For them, the Dayton accord gave no protection.
Not far from their graves lie two wooden markers where Hashem Hatic and Jacuba Nisvet were buried in semi-secrecy in 1992. They had been arrested by the local Serb police and brought to the cemetery on the night of their disappearance in plastic bags. Six other young men were arrested at the same time in Bosanska Gradiska and never seen again. There has been no explanation from the police as to their role in these "disappearances". No names appear on the wooden grave markers.
The elderly thrown from their homes - a sentence of death if ever there was one - appear to be the victims of a group of local policemen who, according to a confidential UN human rights report last month, include between 30 and 40 Serbs displaced from their homes in last year's Muslim- Croat offensive.
They are linked, according to the report, to a Serb "housing commission", "which is harassing, intimidating and burning Muslim homes". Before the Bosnian war, 18,000 Muslims lived in Bosanska Gradiska and Dubrava. Only 2,000 are left.