Realistic Pencil Portrait

I'm seeking an expert artist to create a photorealistic pencil drawing of a single person. The subject should be depicted in a serious expression.

Requirements:
- Expertise in pencil drawing
- Ability to create lifelike portraits
- Experience in capturing complex expressions, especially serious ones

Ideal Skills:
- Attention to detail
- Strong understanding of light and shadow
- Previous portfolio of similar work

Please provide samples of your previous work, especially in portraiture.