Elements of treachery
Treachery is present when the
offender commits any of the crimes
against persons,
employing means, methods, or forms in
the execution, which tend directly and specially to
insure its execution,
without risk to the offender arising
from the defense which the offended party might make. (People v. Laurio, G.R.
No. 182523, September 13, 2012) 
In the case of People v. Orense (G.R. No. 213383, June 22, 2015), a credible
eyewitness account established that accused-appellant, upon meeting Lumbera by
the roadside, suddenly fired a sumpak against the latter,
leaving him unable to defend himself or evade the attack. The assault on
Lumbera ensured that accused-appellant would be able to consummate the crime
without risk to his own person, hence, the qualifying circumstance of
treachery.
In the case of People v. Orense (G.R. No. 213383, June 22, 2015), a credible
eyewitness account established that accused-appellant, upon meeting Lumbera by
the roadside, suddenly fired a sumpak against the latter,
leaving him unable to defend himself or evade the attack. The assault on
Lumbera ensured that accused-appellant would be able to consummate the crime
without risk to his own person, hence, the qualifying circumstance of
treachery.