I always been interested in situations like this
1. I convince the girl to kill herself, torturing her emotionally until she snaps
2. Threaten to kill the guy's wife while next to her and describe the things I'll do, but really we're both acting together
3. me and the burly guy look for boulders to stop it in time (trains aren't THAT fast)
You have to find a justifiable reason to use necromancy, how would you do it?
remember that any revived humans are essentially "slaves" which are morally wrong to own.