Iran has accused the U.S. and Israel for the assassination of an Iranian scientist on Saturday amid growing concerns of Iranian nuclear advancements.

Darioush Rezai-Nejad of Tehran was killed and his wife injured by motorcycle-riding gunmen in front of his home, according to the New York Times, marking the fourth Iranian killed possibly linked to the country's nuclear intelligence agency.

Though it is unclear if Rezai-Nejad was linked in any way to Iran's nuclear program, past reports that have since been backtracked have stated he was a physics professor involved in government nuclear projects. Current reports identify him as possibly a doctoral student at Khajeh Nasroldeen Toosi University or an electronics specialist working at the Iranian defense ministry, according to The Telegrpah.

This latest slaying comes during a time where western nations are growing concern a possible nuclear attack by Iran, who has denied allegations of building nuclear bombs.

American experts say the country is rapidly developing their nuclear strategy and has progressed to the near completion of bomb production.

A number of officials linked to Iran's nuclear venture have recently been attacked or killed in the same way as Rezai-Nejad. Iranian President Mahmoud Ahmadinejad has accused Israel and western governments in the past for killing prestigious physicists in an effort to subdue nuclear programs in Iran.

Fereydoon Abbasi, who currently spearheads Iran's Atomic Energy Organization, was attacked last Nov. after a passing motorcyclist amid heavy traffic placed an unnoticeable magnetic bomb under his car. Both Abbasi and his wife survived the attack but were reportedly injured.

Nuclear physicist and colleague of Abbasi, Majid Shahriari, was killed the same day in the say way as the attack on Abbasi.

Israel has been linked to the killings as suspects involved in the murder of an Iranian particle physicist, Masoud Ali Mohammadi, who was killed in the same way, have admitted they were working under command of Israel, as reported in The New York Times.

According to the Telegraph, many other nuclear physicists who were possibly linked to the Iranian nuclear bomb effort were attacked or proposed missing as evidence begins to appear of Iranian leads regarding bomb making.

The Telegraph reports that Iran plans to mount a centrifuge at a recently identified underground nuclear plant in Qom along with reports of increased uranium production.

Neither Israel nor the U.S. has commented regarding the murder of Rezai-Nejad or plans to sabotage or extinguish Iranian nuclear intelligence acceleration.