Risa

What I like about this is that in Star Trek Adventures, a 1 always counts as two successes.

So, normal difficulty for operating the transporter is 2, but O'Brien is clearly in the transporter room, which reduces the difficulty by 1. We don't know if the ensign started out on a transporter pad, or if the intent was to beam her to one, but under normal circumstances, the highest difficulty for the roll would be 3.

O'Brien has base two dice, and we know he got a 1 on the one the one die in the meme, which is already two successes. The only official stats for O'Brien are in the DS9 Player Characters pdf, and he has 10 Control + 5 Engineering, so if he rolls 15 or less (75% chance) he gets that additional success needed. He also has Focus in Transporters, so on a 5 or less (25% chance) he scores an additional success on top of the first.

Transporter rolls are also aided by the ship, which means the Enterprise D gets to roll one die, and the official Enterprise stats give it a 9 Sensors + 2 Engineering, so it needs to roll an 11 or less (55% chance) to score one success, and ships always roll with Focus, so on a 2 or less (10% chance) to get two successes total.

Also, O'Brien has the Technical Expertise Talent, and whenever he rolls a task aided by the ship's Sensors Attribute, which is the case here, he can re-roll one die including the die that the ship rolled.

Of course, there could be a situation where this particular difficulty was increased by the GM for some reason, but O'Brien should know that before rolling, and could have purchased additional dice with Momentum, or Threat if the Momentum pool was tapped. The likelihood of O'Brien of all characters failing a transporters roll so badly that someone dies is just incredibly small.

All of which is to say that Chief Miles Edward O'Brien murdered that woman.