Section 97 lays down that every person has a right to defend the property of himself or any other person against any act which is an offence falling under the definition of theft, robbery, mischief or criminal trespass or an attempt to commit such offence.
Section 105 lies down that the right of private defence of property commences when a reasonable apprehension of danger to the property commences.
The right of private defence of property against theft continues till (i) the offender has affected his retreat with the property, or either (ii) the assistance of the public authorities is obtained, or (iii) the property has been recovered.
The right of private defence of property against robbery continues as long as (i) the offender causes or attempts to cause to any person death or hurt or wrongful restraint, or (ii) as long as the fear of instant death, or Of instant hurt or of instant personal restraint continues.
The right of private defence of property against criminal trespass or mischief continues as long as the house-trespass which has begun by such house-breaking continues.
The right of private defence of property extends to the voluntary causing of death or of any other harm to the wrongdoer, if the offence, the committing of which or the attempting to commit which, occasions the exercise of the right, be an offence of any of the following description, viz., robbery, house breaking by night, mischief by fire to building, tent or vessel used as a human dwelling or as a place for the custody of property, or theft, mischief or houses-trespass causing apprehension of death or grievous hurt. (S. 103).
Section 104 lays down that if the offence be theft, mischief or criminal trespass, i.e., not of any of the description noted above, the right does not extend to the voluntary causing of death, but does extend to the voluntary causing to the wrongdoer of any harm other than death.
The right of private defence of property does not justify the causing of death in all cases in which theft, mischief or house-trespass is being committed. It is only when the act which amounts to the offence is such as per se to cause a reasonable apprehension that death or grievous hurt will result, the causing of death is justified.
Section 99 lays down, that there is no right of private defence (i) against an act which does not reasonably cause the apprehension of death or of grievous hurt, if done, or attempted to be done, by a public servant or by the direction of a public servant acting in good faith under colour of his office, though that direction may not be strictly justifiable by law; (ii) in cases in which there is time to have recourse to the protection of the public authorities; (iii) nor does the right of private defence extend to the inflicting of more harm than it is necessary to inflict for the purpose of defence.
P has exceeded his right of private defence of property. The case does not fall under Section 105 where the causing of death could be justified.
On his raising an alarm the thief beats a retreat and hence he was not justified in killing him. His case is covered by Exception 2 to Section 300, and he is guilty of culpable homicide not amounting to murder.