We report time-resolved photoelectron spectroscopy of the $3s3p$ doubly excited states of helium dressed by a strong near-infrared (NIR) laser field. Using synchronized XUV free-electron-laser and 800-nm NIR laser pulses, we observe a pronounced delay-dependent shift of resonance-related spectral minima together with the emergence of additional structures around the NIR sideband energy. Ab initio theoretical calculations support these observations and identify the features as signatures of NIR-induced coupling of the bright $\left(3s3p{}^1{P}^o\right)$ autoionizing state to nearby dark $({}^{1}D^e \text{and} {}^{1}S^e)$ resonances below the $N=3$ threshold. A multichannel Fano resonance analysis of the measured spectra yields delay-dependent line-shape parameters and resonance energies, establishing a quantitative route to characterize and control correlated two-electron resonances in strong laser fields.

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• Atomic & molecular processes in external fields
• Atomic spectra
• Autoionization & Auger processes
• Single- and few-photon ionization & excitation
• Strong electromagnetic field effects